Substitute "/" with $opt_s in tag names as well as branch names

In 'git cvsimport' changes "/" to "-" (or $opt_s) in branch names,
but not in tag names, which is inconsistent.

Signed-off-by: Junio C Hamano <junkio@cox.net>

git-cvsimport.perl

@@ -649,6 +649,7 @@ ($$)
 	        my($xtag) = $tag;
 		$xtag =~ s/\s+\*\*.*$//; # Remove stuff like ** INVALID ** and ** FUNKY **
 		$xtag =~ tr/_/\./ if ( $opt_u );
+		$xtag =~ s/[\/]/$opt_s/g;
 
 		my $pid = open2($in, $out, 'git-mktag');
 		print $out "object $cid\n".