Fix try jobs not within a gclient checkout

trychange.py

Index: trychange.py
diff --git a/trychange.py b/trychange.py
index d4eede1fab2da275ecf3c6e1c95500ffabebdf5f..7cd90b9b0696302bd6584c8bb099a763e1575645 100755
--- a/trychange.py
+++ b/trychange.py
@@ -163,6 +163,8 @@ class SCM(object):
       root = os.path.abspath(self.gclient_root)
     else:
       root = gclient_utils.FindGclientRoot(cur)
+    if not root:
+      root = cur
     assert cur.startswith(root), (root, cur)
     while cur.startswith(root):
       filepath = os.path.join(cur, filename)