The jobgenerators only allow for one jobgeneration at a time

1. Add 200.000 dummy nonexisting domains to an empty domains table 2. start a snapshot harvest of 10 objects (to avoid harvesting too much in case any of the domains too exist) 3. Wait until jobs is being generated for the snapshot harvest 4. start a selective harvest of netarkivet. 5. The selective harvest should start generating jobs before the snapshot harvest has finished generating jobs.