One of the reasons I really like Electrum is that it has really good address control. I can import addresses, export addresses, turn off change addresses, and by prioritizing an address, I can send from that address alone, to another address.

The bug is this:

1) Import a private key for a foreign address.

2) Prioritize that address when sending, but leave all other addresses unprioritized.

3) Initiate a payment. When doing so, an error is returned. The error in the server log is this:

error: {u'message': u'TX rejected', u'code': -22} [u'']

I've tested this when sending the transaction through my new Electrum server and other Electrum Servers.