Merge branch 'jk/push-force-with-lease-creation' into maint

"git push --force-with-lease" already had enough logic to allow
ensuring that such a push results in creation of a ref (i.e. the
receiving end did not have another push from sideways that would be
discarded by our force-pushing), but didn't expose this possibility
to the users.  It does so now.

* jk/push-force-with-lease-creation:
  t5533: make it pass on case-sensitive filesystems
  push: allow pushing new branches with --force-with-lease
  push: add shorthand for --force-with-lease branch creation
  Documentation/git-push: fix placeholder formatting

Documentation/git-push.txt

@@ -198,10 +198,11 @@ branch we have for it.
 +
 `--force-with-lease=<refname>:<expect>` will protect the named ref (alone),
 if it is going to be updated, by requiring its current value to be
-the same as the specified value <expect> (which is allowed to be
+the same as the specified value `<expect>` (which is allowed to be
 different from the remote-tracking branch we have for the refname,
 or we do not even have to have such a remote-tracking branch when
-this form is used).
+this form is used).  If `<expect>` is the empty string, then the named ref
+must not already exist.
 +
 Note that all forms other than `--force-with-lease=<refname>:<expect>`
 that specifies the expected current value of the ref explicitly are

remote.c

@@ -1544,8 +1544,7 @@ void set_ref_status_for_push(struct ref *remote_refs, int send_mirror,
 		 * branch.
 		 */
 		if (ref->expect_old_sha1) {
-			if (ref->expect_old_no_trackback ||
-			    oidcmp(&ref->old_oid, &ref->old_oid_expect))
+			if (oidcmp(&ref->old_oid, &ref->old_oid_expect))
 				reject_reason = REF_STATUS_REJECT_STALE;
 			else
 				/* If the ref isn't stale then force the update. */
@@ -2294,6 +2293,8 @@ int parse_push_cas_option(struct push_cas_option *cas, const char *arg, int unse
 	entry = add_cas_entry(cas, arg, colon - arg);
 	if (!*colon)
 		entry->use_tracking = 1;
+	else if (!colon[1])
+		hashclr(entry->expect);
 	else if (get_sha1(colon + 1, entry->expect))
 		return error("cannot parse expected object name '%s'", colon + 1);
 	return 0;
@@ -2343,7 +2344,7 @@ static void apply_cas(struct push_cas_option *cas,
 		if (!entry->use_tracking)
 			hashcpy(ref->old_oid_expect.hash, cas->entry[i].expect);
 		else if (remote_tracking(remote, ref->name, &ref->old_oid_expect))
-			ref->expect_old_no_trackback = 1;
+			oidclr(&ref->old_oid_expect);
 		return;
 	}
 
@@ -2353,7 +2354,7 @@ static void apply_cas(struct push_cas_option *cas,
 
 	ref->expect_old_sha1 = 1;
 	if (remote_tracking(remote, ref->name, &ref->old_oid_expect))
-		ref->expect_old_no_trackback = 1;
+		oidclr(&ref->old_oid_expect);
 }
 
 void apply_push_cas(struct push_cas_option *cas,

remote.h

@@ -89,7 +89,6 @@ struct ref {
 		force:1,
 		forced_update:1,
 		expect_old_sha1:1,
-		expect_old_no_trackback:1,
 		deletion:1,
 		matched:1;
 

t/t5533-push-cas.sh

@@ -191,4 +191,42 @@ test_expect_success 'cover everything with default force-with-lease (allowed)' '
 	test_cmp expect actual
 '
 
+test_expect_success 'new branch covered by force-with-lease' '
+	setup_srcdst_basic &&
+	(
+		cd dst &&
+		git branch branch master &&
+		git push --force-with-lease=branch origin branch
+	) &&
+	git ls-remote dst refs/heads/branch >expect &&
+	git ls-remote src refs/heads/branch >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'new branch covered by force-with-lease (explicit)' '
+	setup_srcdst_basic &&
+	(
+		cd dst &&
+		git branch branch master &&
+		git push --force-with-lease=branch: origin branch
+	) &&
+	git ls-remote dst refs/heads/branch >expect &&
+	git ls-remote src refs/heads/branch >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'new branch already exists' '
+	setup_srcdst_basic &&
+	(
+		cd src &&
+		git checkout -b branch master &&
+		test_commit F
+	) &&
+	(
+		cd dst &&
+		git branch branch master &&
+		test_must_fail git push --force-with-lease=branch: origin branch
+	)
+'
+
 test_done