Fix /mapreduce/pipeline to properly ZipImport
Fix /mapreduce/pipeline to properly ZipImport

Test Plan:
Craig's review
(ZipImport's only happen in production, so hard to test locally)

Reviewers: csilvers

Differential Revision: http://phabricator.khanacademy.org/D2281

VirusTotal/appengine-pipelines,aozarov/appengine-pipelines,aozarov/appengine-pipelines,googlecloudplatform/appengine-pipelines,vendasta/appengine-pipelines,aozarov/appengine-pipelines,googlecloudplatform/appengine-pipelines,VirusTotal/appengine-pipelines,vendasta/appengine-pipelines,GoogleCloudPlatform/appengine-pipelines,googlecloudplatform/appengine-pipelines,googlecloudplatform/appengine-pipelines,aozarov/appengine-pipelines,Loudr/appengine-pipelines,Loudr/appengine-pipelines,Loudr/appengine-pipelines,VirusTotal/appengine-pipelines,vendasta/appengine-pipelines,vendasta/appengine-pipelines,aozarov/appengine-pipelines,Loudr/appengine-pipelines,Loudr/appengine-pipelines,VirusTotal/appengine-pipelines,vendasta/appengine-pipelines,GoogleCloudPlatform/appengine-pipelines,VirusTotal/appengine-pipelines,GoogleCloudPlatform/appengine-pipelines,GoogleCloudPlatform/appengine-pipelines,GoogleCloudPlatform/appengine-pipelines,googlecloudplatform/appengine-pipelines