Completion after commands with paths.

[Peter Stephenson <pws@xxxxxxxxxxxxxxxxxxxxxxxxx>]

Some completion functions are too finnicky about looking at the command
names: they should be looking at the basenames, and instead are looking at
the full string.  The problem I had was in _ssh when I was calling scp with
a full path; the case statement doesn't take this into account.  That's an
easy fix, but there may be a lot of other functions with this bug (or
issue, as we ought to call it now we have a tracking system), and I don't
have time to look now.

pws