git-svn: Fix merge detecting with rewrite-root

Detecting of merges from svn:mergeinfo or svk merge tickets failed
with rewrite-root option. This fixes it.

Signed-off-by: Tuomas Suutari <tuomas.suutari@gmail.com>
Acked-by: Eric Wong <normalperson@yhbt.net>
diff --git a/git-svn.perl b/git-svn.perl
index 1a26843..aceeca5 100755
--- a/git-svn.perl
+++ b/git-svn.perl
@@ -2998,7 +2998,7 @@
 	for my $ticket ( @tickets ) {
 		my ($uuid, $path, $rev) = split /:/, $ticket;
 		if ( $uuid eq $self->ra_uuid ) {
-			my $url = $self->rewrite_root || $self->{url};
+			my $url = $self->{url};
 			my $repos_root = $url;
 			my $branch_from = $path;
 			$branch_from =~ s{^/}{};
@@ -3206,7 +3206,7 @@
 	# are now marked as merge, we can add the tip as a parent.
 	my @merges = split "\n", $mergeinfo;
 	my @merge_tips;
-	my $url = $self->rewrite_root || $self->{url};
+	my $url = $self->{url};
 	my $uuid = $self->ra_uuid;
 	my %ranges;
 	for my $merge ( @merges ) {