The bundle2 part was always being generated, even for non-treemanifest repos
(because fastmanifest imports the treemanifest module, so the b2partsgenerator
gets registered). This cause pushes to break in any repo with fastmanifest
enabled.
Summary:
To enable pushing between peers (and eventually pushing to the server), let's
teach bundle creation to include the trees being pushed.
Test Plan: Adds a test
Reviewers: #mercurial, quark
Reviewed By: quark
Subscribers: quark, mjpieters
Differential Revision: https://phabricator.intern.facebook.com/D4957456
Signature: t1:4957456:1493266296:67f98a2b3d691644bde9098a713d05266f349cde
