git leaves behind .git/COMMIT_EDITMSG non-shared in --shared non-bare repo

[Yaroslav Halchenko <yoh@onerussian.com>]

Not sure for what batch operations that file is actually useful, but the
story is that if we have a shared git repo (I know -- might not be as
common of a situation but possible and allowed to happen), then if one
from the shared group commits within that repository, it becomes
impossible for another person to commit.  

git does take care about chmod'ing all the files under .git/objects etc
for --shared operation, but leaves .git/COMMIT_EDITMSG at the
mercy of user's umask.  IMHO correct resolution, if leaving that file
behind is necessary, is to chmod it in the same fashion as any other
internal .git file in --shared mode -- with group write permission.

I have reproduced that behavior with today's version of git as of
2.7.0.rc1.5.gf3adf45.

-- 
Yaroslav O. Halchenko
Center for Open Neuroscience     http://centerforopenneuroscience.org
Dartmouth College, 419 Moore Hall, Hinman Box 6207, Hanover, NH 03755
Phone: +1 (603) 646-9834                       Fax: +1 (603) 646-1419
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