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![Kevin Willford](/assets/img/avatar_default.png)
The `rebase` family of Git commands avoid applying patches that were already integrated upstream. They do that by using the revision walking option that computes the patch IDs of the two sides of the rebase (local-only patches vs upstream-only ones) and skipping those local patches whose patch ID matches one of the upstream ones. In many cases, this causes unnecessary churn, as already the set of paths touched by a given commit would suffice to determine that an upstream patch has no local equivalent. This hurts performance in particular when there are a lot of upstream patches, and/or large ones. Therefore, let's introduce the concept of a "diff-header-only" patch ID, compare those first, and only evaluate the "full" patch ID lazily. Please note that in contrast to the "full" patch IDs, those "diff-header-only" patch IDs are prone to collide with one another, as adjacent commits frequently touch the very same files. Hence we now have to be careful to allow multiple hash entries with the same hash. We accomplish that by using the hashmap_add() function that does not even test for hash collisions. This also allows us to evaluate the full patch ID lazily, i.e. only when we found commits with matching diff-header-only patch IDs. We add a performance test that demonstrates ~1-6% improvement. In practice this will depend on various factors such as how many upstream changes and how big those changes are along with whether file system caches are cold or warm. As Git's test suite has no way of catching performance regressions, we also add a regression test that verifies that the full patch ID computation is skipped when the diff-header-only computation suffices. Signed-off-by: Kevin Willford <kcwillford@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
232 lines
5 KiB
Bash
Executable file
232 lines
5 KiB
Bash
Executable file
#!/bin/sh
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test_description='test git rev-list --cherry-pick -- file'
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. ./test-lib.sh
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# A---B---D---F
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# \
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# \
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# C---E
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#
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# B changes a file foo.c, adding a line of text. C changes foo.c as
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# well as bar.c, but the change in foo.c was identical to change B.
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# D and C change bar in the same way, E and F differently.
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test_expect_success setup '
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echo Hallo > foo &&
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git add foo &&
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test_tick &&
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git commit -m "A" &&
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git tag A &&
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git checkout -b branch &&
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echo Bello > foo &&
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echo Cello > bar &&
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git add foo bar &&
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test_tick &&
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git commit -m "C" &&
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git tag C &&
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echo Dello > bar &&
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git add bar &&
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test_tick &&
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git commit -m "E" &&
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git tag E &&
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git checkout master &&
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git checkout branch foo &&
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test_tick &&
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git commit -m "B" &&
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git tag B &&
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echo Cello > bar &&
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git add bar &&
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test_tick &&
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git commit -m "D" &&
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git tag D &&
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echo Nello > bar &&
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git add bar &&
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test_tick &&
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git commit -m "F" &&
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git tag F
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'
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cat >expect <<EOF
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<tags/B
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>tags/C
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EOF
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test_expect_success '--left-right' '
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git rev-list --left-right B...C > actual &&
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git name-rev --stdin --name-only --refs="*tags/*" \
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< actual > actual.named &&
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test_cmp actual.named expect
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'
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test_expect_success '--count' '
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git rev-list --count B...C > actual &&
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test "$(cat actual)" = 2
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'
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test_expect_success '--cherry-pick foo comes up empty' '
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test -z "$(git rev-list --left-right --cherry-pick B...C -- foo)"
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'
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cat >expect <<EOF
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>tags/C
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EOF
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test_expect_success '--cherry-pick bar does not come up empty' '
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git rev-list --left-right --cherry-pick B...C -- bar > actual &&
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git name-rev --stdin --name-only --refs="*tags/*" \
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< actual > actual.named &&
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test_cmp actual.named expect
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'
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test_expect_success 'bar does not come up empty' '
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git rev-list --left-right B...C -- bar > actual &&
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git name-rev --stdin --name-only --refs="*tags/*" \
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< actual > actual.named &&
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test_cmp actual.named expect
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'
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cat >expect <<EOF
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<tags/F
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>tags/E
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EOF
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test_expect_success '--cherry-pick bar does not come up empty (II)' '
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git rev-list --left-right --cherry-pick F...E -- bar > actual &&
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git name-rev --stdin --name-only --refs="*tags/*" \
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< actual > actual.named &&
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test_cmp actual.named expect
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'
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cat >expect <<EOF
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+tags/F
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=tags/D
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+tags/E
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=tags/C
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EOF
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test_expect_success '--cherry-mark' '
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git rev-list --cherry-mark F...E -- bar > actual &&
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git name-rev --stdin --name-only --refs="*tags/*" \
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< actual > actual.named &&
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test_cmp actual.named expect
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'
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cat >expect <<EOF
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<tags/F
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=tags/D
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>tags/E
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=tags/C
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EOF
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test_expect_success '--cherry-mark --left-right' '
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git rev-list --cherry-mark --left-right F...E -- bar > actual &&
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git name-rev --stdin --name-only --refs="*tags/*" \
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< actual > actual.named &&
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test_cmp actual.named expect
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'
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cat >expect <<EOF
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tags/E
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EOF
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test_expect_success '--cherry-pick --right-only' '
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git rev-list --cherry-pick --right-only F...E -- bar > actual &&
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git name-rev --stdin --name-only --refs="*tags/*" \
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< actual > actual.named &&
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test_cmp actual.named expect
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'
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test_expect_success '--cherry-pick --left-only' '
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git rev-list --cherry-pick --left-only E...F -- bar > actual &&
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git name-rev --stdin --name-only --refs="*tags/*" \
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< actual > actual.named &&
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test_cmp actual.named expect
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'
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cat >expect <<EOF
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+tags/E
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=tags/C
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EOF
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test_expect_success '--cherry' '
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git rev-list --cherry F...E -- bar > actual &&
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git name-rev --stdin --name-only --refs="*tags/*" \
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< actual > actual.named &&
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test_cmp actual.named expect
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'
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cat >expect <<EOF
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1 1
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EOF
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test_expect_success '--cherry --count' '
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git rev-list --cherry --count F...E -- bar > actual &&
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test_cmp actual expect
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'
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cat >expect <<EOF
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2 2
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EOF
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test_expect_success '--cherry-mark --count' '
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git rev-list --cherry-mark --count F...E -- bar > actual &&
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test_cmp actual expect
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'
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cat >expect <<EOF
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1 1 2
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EOF
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test_expect_success '--cherry-mark --left-right --count' '
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git rev-list --cherry-mark --left-right --count F...E -- bar > actual &&
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test_cmp actual expect
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'
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test_expect_success '--cherry-pick with independent, but identical branches' '
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git symbolic-ref HEAD refs/heads/independent &&
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rm .git/index &&
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echo Hallo > foo &&
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git add foo &&
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test_tick &&
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git commit -m "independent" &&
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echo Bello > foo &&
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test_tick &&
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git commit -m "independent, too" foo &&
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test -z "$(git rev-list --left-right --cherry-pick \
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HEAD...master -- foo)"
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'
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cat >expect <<EOF
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1 2
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EOF
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test_expect_success '--count --left-right' '
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git rev-list --count --left-right C...D > actual &&
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test_cmp expect actual
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'
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# Corrupt the object store deliberately to make sure
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# the object is not even checked for its existence.
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remove_loose_object () {
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sha1="$(git rev-parse "$1")" &&
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remainder=${sha1#??} &&
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firsttwo=${sha1%$remainder} &&
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rm .git/objects/$firsttwo/$remainder
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}
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test_expect_success '--cherry-pick avoids looking at full diffs' '
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git checkout -b shy-diff &&
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test_commit dont-look-at-me &&
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echo Hello >dont-look-at-me.t &&
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test_tick &&
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git commit -m tip dont-look-at-me.t &&
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git checkout -b mainline HEAD^ &&
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test_commit to-cherry-pick &&
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remove_loose_object shy-diff^:dont-look-at-me.t &&
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git rev-list --cherry-pick ...shy-diff
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'
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test_done
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