Add post-merge hook, related documentation, and tests.

The post-merge hook enables one to hook in for `git pull` operations in order
to check and/or change attributes of a work tree from the hook.  As an example,
it can be used in combination with a pre-commit hook to save/restore file
ownership and permissions data (or file ACLs) within the repository and
transparently update the working tree after a `git pull` operation.

Signed-off-by: Josh England <jjengla@sandia.gov>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/Documentation/hooks.txt b/Documentation/hooks.txt
index c39edc57c4..50535a7983 100644
--- a/Documentation/hooks.txt
+++ b/Documentation/hooks.txt
@@ -87,6 +87,18 @@ parameter, and is invoked after a commit is made.
 This hook is meant primarily for notification, and cannot affect
 the outcome of `git-commit`.
 
+post-merge
+-----------
+
+This hook is invoked by `git-merge`, which happens when a `git pull`
+is done on a local repository.  The hook takes a single parameter, a status
+flag specifying whether or not the merge being done was a squash merge.
+This hook cannot affect the outcome of `git-merge`.
+
+This hook can be used in conjunction with a corresponding pre-commit hook to
+save and restore any form of metadata associated with the working tree
+(eg: permissions/ownership, ACLS, etc).
+
 [[pre-receive]]
 pre-receive
 -----------