bug 391137: when building a path to the httpd.js and server.js MochiTest scripts on Windows, add a directory separator between the root dir and appended dirs so two dirs don't run together, creating an invalid path r=gavin, r=sayrer

testing/mochitest/runtests.pl.in

@@ -315,7 +315,7 @@ sub winPathFromDir {
   my ($volume,$directories,$file) =
     File::Spec->splitpath(substr($path, $matchlen), 1);
   my @dirs = File::Spec->splitdir( $directories );
-  return $bestmatch . join "\\", @dirs;
+  return $bestmatch . "\\" . join "\\", @dirs;
 }
 
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