Summary:
Ref T4245. Make `/diffusion/123/` work, but redirect the user to `/diffusion/XYZ/` if the repository has a callsign.
(Right now, every repository has a callsign, so this always redirects.)
Also redirect `/R123:abcdef` if the repository has a callsign.
Also also, move the Pull garbage collector somewhere more sensible.
Test Plan:
- Added test coverage.
- Visited `/diffusion/1/`, was redirected.
- Visited `/diffusion/R1:abcdef`, was redirected.
- Browsed Diffusion normally.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T4245
Differential Revision: https://secure.phabricator.com/D15301
