Error importing module for pending tasks in application engine

Question

I create a task using deferred.defer. Tasks do not complete with the following error.

Permanent failure attempting to execute task Traceback (most recent call last): File "/base/python27_runtime/python27_lib/versions/1/google/appengine/ext/deferred/deferred.py", line 298, in post self.run_from_request() File "/base/python27_runtime/python27_lib/versions/1/google/appengine/ext/deferred/deferred.py", line 293, in run_from_request run(self.request.body) File "/base/python27_runtime/python27_lib/versions/1/google/appengine/ext/deferred/deferred.py", line 133, in run raise PermanentTaskFailure(e) PermanentTaskFailure: cannot import name location 

location is a module in our source code.

Additional Information:

I also have third-party libraries in the lib folder. I have a third_party_libs.py file

 import os import sys sys.path.append(os.path.join(os.path.dirname(__file__), 'lib')) 

I am including this file in the appropriate places. I also tried to include this in all __init__.py files. The error is especially cryptic, and the stack trace does not point to any place in my source. Any pointers on how to debug this will be appreciated.