There are two issues with test skipping that I ran into with my work-in-progress M1 configuration: 1. Perforce tests were set up to skip if the P4 module wasn't available, but at some point we had an import of P4Exception snuck in that wasn't properly guarded. This change makes it so that we properly skip the test without hitting `ImportError`. 2. Once upon a time, paramiko just allowed `SocketError` to raise when port 22 was closed, but now it has its own error class. Testing Done: Ran unit tests.