config: match both symlink & realpath versions in IncludeIf.gitdir:*

Change the conditional inclusion mechanism to support
e.g. gitdir:~/git_tree/repo where ~/git_tree is a symlink to
/mnt/stuff/repo.

This worked in the initial version of this facility[1], but regressed
later in the series while solving a related bug[2].

Now gitdir: will match against the symlinked
path (e.g. gitdir:~/git_tree/repo) in addition to the current
/mnt/stuff/repo path.

Since this is already in a release version note in the documentation
that this behavior changed, so users who expect their configuration to
work on both v2.13.0 and some future version of git with this fix
aren't utterly confused.

1. commit 3efd0bedc6 ("config: add conditional include", 2017-03-01)
2. commit 86f9515708 ("config: resolve symlinks in conditional
   include's patterns", 2017-04-05)

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 475e874d51..302b8af192 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -140,6 +140,16 @@ A few more notes on matching via `gitdir` and `gitdir/i`:
 
  * Symlinks in `$GIT_DIR` are not resolved before matching.
 
+ * Both the symlink & realpath versions of paths will be matched
+   outside of `$GIT_DIR`. E.g. if ~/git is a symlink to
+   /mnt/storage/git, both `gitdir:~/git` and `gitdir:/mnt/storage/git`
+   will match.
++
+This was not the case in the initial release of this feature in
+v2.13.0, which only matched the realpath version. Configuration that
+wants to be compatible with the initial release of this feature needs
+to either specify only the realpath version, or both versions.
+
  * Note that "../" is not special and will match literally, which is
    unlikely what you want.