work requests aborted and only partially restarted

Describe the bug

In work request 174863 lots of started work requests are aborted without any visible reason. In case of sbuild-work-requests it even seems to be that those are automatically restarted. Anyway, the restarted (and successful) work requests are not considered in the other work requests, whose status is still "aborted".

I manually retried 174887 (amd64 autopkgtests for msgpack-c) and 174881 (all autopkgtests for mosquitto) and everything worked fine now. Is there a reason for the initial abort? Would it be possible to automatically restart everything after a non-manual abort?

How to reproduce the bug

Work request 174951, which was started a few minutes afterwards (with the same changes file), did run without problems. So I am afraid this can not be reproduced.

Runtime environment

Everything ran on debusine.debian.net.