If $hash_parent is defined, shortlog now limits the list of commits at
those between $hash_parent (exclusive) and $hash (inclusive).
Signed-off-by: NGiuseppe Bilotta <giuseppe.bilotta@gmail.com>
Acked-by: NPetr Baudis <pasky@suse.cz>
Signed-off-by: NShawn O. Pearce <spearce@spearce.org>