Illegal jobs, warrant issues and particular scenario
You only discard an Active Job if you get issued a warrant while working that job.

Firefly Rules, pg 14


  If you receive a Warrant while Working a Job, discard the Job, returning it to the discard pile of the issuing Contact.


This is the only mention of discarding Active Jobs when you get a Warrant. You only lose the Job you are using your Work action for, you don't lose other Jobs, and gaining a Warrant outside of a Work action doesn't effect your current Jobs at all.