msysGit generates version strings with text appended which cannot
be used with vcompare; trying to use them generates a Tcl error.
Limit git_version to the first three digits which are the real git
version to avoid this error.
Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net> Signed-off-by: Paul Mackerras <paulus@samba.org>