[PATCH STABLE] revbranchcache: special case nullrev

[Yuya Nishihara]

On Fri, 22 May 2015 21:59:30 -0700, Durham Goode wrote:
> # HG changeset patch
> # User Durham Goode <durham at fb.com>
> # Date 1432357020 25200
> #      Fri May 22 21:57:00 2015 -0700
> # Node ID 912ff2370836f46461218a68212c3c253d2bc5c7
> # Parent  f2b98dacb37ddd6713b11a1a871fcdbbc5fd8bb2
> revbranchcache: special case nullrev
> 
> hg log -r 'branch(.)' was causing a stack trace if the user was on the nullrev
> because it tried to access position -1 in the rev branch cache. This patch
> special cases the nullrev to avoid the cache.
> 
> diff --git a/mercurial/branchmap.py b/mercurial/branchmap.py
> --- a/mercurial/branchmap.py
> +++ b/mercurial/branchmap.py
> @@ -338,6 +338,9 @@ class revbranchcache(object):
>      def branchinfo(self, rev):
>          """Return branch name and close flag for rev, using and updating
>          persistent cache."""
> +        if rev == nullrev:
> +            return self._branchinfo(rev)

_branchinfo() calls _setcachedata() with negative rev, which is probably wrong.

I have a patch that will do "return changelog.branchinfo(rev)" instead, and
another patch for "children(branch(null))" issue.

Regards,