Fixing push -> append in indexing script.

BUG=None
TEST=None

Review URL: http://codereview.chromium.org/6711018

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/gsd_generate_index@78606 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/gsd_generate_index.py b/gsd_generate_index.py
index 6d0dc4d..631c354 100755
--- a/gsd_generate_index.py
+++ b/gsd_generate_index.py
@@ -156,7 +156,7 @@
       GenerateIndex(d, children, directories, options)
     except Exception, e:
       mutex.acquire()
-      errors.push(e)
+      errors.append(e)
       print str(e)
       mutex.release()