When testing the incoming cgit lister on that instance: http://hdiff.luite.com/cgit/,
the lister successfully retrieves all hosted repositories but fails to flush the
results into the local lister database (python3 process ended up hanging).

The issue came from the fact the underlying db transaction was too large.
The solution to resolve the issue is to split repo models into smaller
chunks to avoid that behavior. Processing like this also flushes results
to database more frequently.

Related T1659