[PATCH] rerere: exit silently on "forget" when rerere is disabled

[Jeff King <peff@peff.net>]

On Thu, May 14, 2015 at 12:19:25PM -0700, Junio C Hamano wrote:

> > It looks like we need to pay more attention to the return value of
> > setup_rerere, which is what is supposed to take the lock.
> 
> Good spotting.  The normal rerere does check, but rerere-forget
> codepath seems to forget it.

Here's a patch.

-- >8 --
Subject: rerere: exit silently on "forget" when rerere is disabled

If you run "git rerere forget foo" in a repository that does
not have rerere enabled, git hits an internal error:

  $ git init -q
  $ git rerere forget foo
  fatal: BUG: attempt to commit unlocked object

The problem is that setup_rerere() will not actually take
the lock if the rerere system is disabled. We should notice
this and return early. We can return with a success code
here, because we know there is nothing to forget.

Signed-off-by: Jeff King <peff@peff.net>
---
 rerere.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/rerere.c b/rerere.c
index 31644de..94aea9a 100644
--- a/rerere.c
+++ b/rerere.c
@@ -659,6 +659,8 @@ int rerere_forget(struct pathspec *pathspec)
 		return error("Could not read index");
 
 	fd = setup_rerere(&merge_rr, RERERE_NOAUTOUPDATE);
+	if (fd < 0)
+		return 0;
 
 	unmerge_cache(pathspec);
 	find_conflict(&conflict);
-- 
2.4.1.396.g7ba6d7b