Fix some release browsing in snapshot context views
Some releases cannot currently been browsed in the webapp when specifying their name as a query parameter in snapshot context views.
For instance this link should point to the source tree of the 2.0 release of Python but a 404 error is raised instead.
The issue is due to the associated snapshot content being truncated to 1000 branches when the webapp retrieves it.
Migrated from T2108 (view on Phabricator)