Recently the msysgit repository has got a '1.6.1-msysgit1'
tag, which, when used to build the git version, is not
handled gracefully by the git-gui version code.
This patch changes the regular expressions to fix it, and
removes the hardcoded 'rc' string. Now git-gui can accept
a version tail like '.foo123.GIT.bar.456.7.g89ab'
Signed-off-by: Alexander Gavrilov <angavrilov@gmail.com> Signed-off-by: Shawn O. Pearce <spearce@spearce.org>