python - ip: Use get_loader when available.

Log Message:
-----------
Use get_loader when available.

Trim out a special exception printer as postgresql.exceptions.Error now
prints all of the details. Subsequently, don't bother altering the printed
traceback with compile errors(looked into the stack one level to keep the
printed traceback small).

Modified Files:
--------------
ip/src:
python.py (r1.10 -> r1.11)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/ip/src/python.py.diff?r1=1.10&r2=1.11)