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 tool large.
The solution to resolve the issue is to split repo models into smaller
chunks to avoid that behavior. Proceesing like this also flushes results
to database more frequently.
Related T1659