sub usage() {
print STDERR <<END;
-Usage: ${\basename $0} # fetch/update GIT from SVN
+usage: ${\basename $0} # fetch/update GIT from SVN
[-o branch-for-HEAD] [-h] [-v] [-l max_rev] [-R repack_each_revs]
[-C GIT_repository] [-t tagname] [-T trunkname] [-b branchname]
[-d|-D] [-i] [-u] [-r] [-I ignorefilename] [-s start_chg]