Use $1 instead of \1 to avoid perl warnings in log files.

Bug #325453

webtools/bonsai/cvsquery.cgi

@@ -193,7 +193,7 @@ $::query_branch = $::FORM{'branch'};
 $::query_branchtype = &ExpectMatchtype($::FORM{'branchtype'});
 $::query_branch = 'HEAD' if !defined($::query_branch);
 if ($::query_branchtype eq 'notregexp' || $::query_branchtype eq 'regexp') {
-    $::query_branch =~ s/\W*([\w-]+).*/\1/;
+    $::query_branch =~ s/\W*([\w-]+).*/$1/;
 } else {
     $::query_branch = &SanitizeRevision($::query_branch);
 }