Prevent obs_import race condition about cavil HOT 3 CLOSED

If you're lucky, you get failed minion jobs on index or unpack. If you're unlucky you get invalid reports.

IMO we need to make sure there is only one job set per package at any given time, because this also impacts performance even for the jobs where it doesn't harm.

from cavil.

The main problem of race conditions should be fixed now. But once Minion has upstream support for batch jobs (probably weeks or months away still) i'd like to switch to those to make lock management easier and a bit safer.

from cavil.

I've not seen an import race condition in a long time, so the problem is probably gone. And there are no new upstream features planned anymore for batch jobs. So i guess we can consider this resolved.

from cavil.