There are two issues with test skipping that I ran into with my

work-in-progress M1 configuration:

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.
Once upon a time, paramiko just allowed SocketError to raise when

   port 22 was closed, but now it has its own error class.

Ran unit tests.