receive-pack: don't pass non-existent refs to post-{receive,update} hooks

When a push specifies deletion of non-existent refs, the post post-receive and
post-update hooks receive them as input/arguments.

For instance, for the following push, where refs/heads/nonexistent is a ref
which does not exist on the remote side:

	git push origin :refs/heads/nonexistent

the post-receive hook receives from standard input:

	<null-sha1> SP <null-sha1> SP refs/heads/nonexistent

and the post-update hook receives as arguments:

	refs/heads/nonexistent

which does not make sense since it is a no-op.

Teach receive-pack not to pass non-existent refs to the post-receive and
post-update hooks. If the push only attempts to delete non-existent refs,
these hooks are not even called.

The update and pre-receive hooks are still notified about attempted
deletion of non-existent refs to give them a chance to inspect the
situation and act on it.

[jc: mild fix-ups to avoid introducing an extra list; also added fixes to
some tests]

Signed-off-by: Pang Yan Han <pangyanhan@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/refs.h b/refs.h
index dfb086e933..4431205338 100644
--- a/refs.h
+++ b/refs.h
@@ -57,7 +57,7 @@ extern void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refn
  */
 extern void add_extra_ref(const char *refname, const unsigned char *sha1, int flags);
 extern void clear_extra_refs(void);
-extern int ref_exists(char *);
+extern int ref_exists(const char *);
 
 extern int peel_ref(const char *, unsigned char *);