[qmtest] debugging qmtest with pdb

[Mark Eichin]

> The problem I have is that when running with pdb, I get exceptions thrown
> that I don't have when running only with python.

I haven't (needed to) in ages, but when I first started, the main
problem was the QM_HOME etc. environment variables - it was easier to
just import pdb and put pdb.set_trace() in the code of my own that I
was debugging, if I remember it correctly...