Earlier, if you changed a staged path into a directory in the work tree,
we happily ran lstat(2) on it and found that it exists, and declared that
the user changed it to a gitlink.
This is wrong for two reasons:
(1) It may be a directory, but it may not be a submodule, and in the
latter case, the change we need to report is "the blob at the path
has disappeared". We need to check with resolve_gitlink_ref() to be
consistent with what "git add" and "git update-index --add" does.
(2) lstat(2) may have succeeded only because a leading component of the
path was turned into a symbolic link that points at something that
exists in the work tree. In such a case, the path itself does not
exist anymore, as far as the index is concerned.
This fixes these breakages in diff-index that the previous patch has
exposed.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff-index and diff-files can get confused in corner cases when an indexed
blob turns into something else in the work tree. This patch adds tests to
expose such breakages.
The test is classified under t2XXX series instead of t4XXX series, because
the ultimate objective is to fix "add -u" (and "commit -a" that shares the
same issue).
Signed-off-by: Junio C Hamano <gitster@pobox.com>
