Looks good to me. Just a nitpick, I would move the condition one line up, so the p definition and it's appending to pool is not separated.

However, looking into the code again, the self.try_to_obtain_new_tasks is called with limit parameter which IMHO correctly specifies the number of tasks, that can currently be handled. The problem is, that try_to_obtain_new_tasks doesn't use that parameter. Maybe it would be worth it, to use it?

I changed the method try_to_obtain_new_tasks so it uses argument limit.

+1

I'd prefer distgit: prefix in commit message, but +1

Merged as 9a2e4b5