Fix url rewriting

Only apply pathTranslation if a path hasn't been rewritten
(they're always relative paths), or if the rewritten path
didn't begin with '/'.

hphp/runtime/base/server/request_uri.cpp

@@ -234,10 +234,14 @@ bool RequestURI::virtualFileExists(const VirtualHost *vhost,
                AttachString);
   if (!vhost->getDocumentRoot().empty()) {
     string fullname = canon.data();
-    while (fullname[0] == '/') {
-      fullname = fullname.substr(1);
+    int i = 0;
+    while (i < fullname.size() && fullname[i] == '/') ++i;
+    if (i) {
+      fullname = fullname.substr(i);
+    }
+    if (!i || !m_rewritten) {
+      fullname = pathTranslation + fullname;
     }
-    fullname = pathTranslation + fullname;
     m_path = fullname;
     m_absolutePath = String(sourceRoot) + m_path;
     processExt();