Force a full GC after importing a project
During a project import, it's possible that new branches are
created by the importer to handle pull requests that have been
created from forked projects, which would increment the
HousekeepingService.increment! before a full garbage collection gets to run. This causes HousekeepingService to skip the full
git gc and move to the incremental repack mode. To ensure that a garbage collection
is run to pack refs and objects, explicitly execute the task.