git-svn: stop passing "-m" to "git rev-list"

rev-list doesn't utilize -m. It happens to eat it silently, so this
bug went unnoticed.

Signed-off-by: Sergey Organov <sorganov@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

perl/Git/SVN.pm

@@ -1636,7 +1636,7 @@ sub has_no_changes {
 	my $commit = shift;
 
 	my @revs = split / /, command_oneline(
-		qw(rev-list --parents -1 -m), $commit);
+		qw(rev-list --parents -1), $commit);
 
 	# Commits with no parents, e.g. the start of a partial branch,
 	# have changes by definition.