Commit IDs should have commit descriptions too.  Warn when a 12 to 40 byte
SHA-1 is used in commit logs.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>