PL/Python: Adjust the regression tests for Python 3.3

PL/Python: Adjust the regression tests for Python 3.3

The string representation of ImportError changed.  Remove printing
that; it's not necessary for the test.

The order in which members of a dict are printed changed.  But this
was always implementation-dependent, so we have just been lucky for a
long time.  Do the printing the hard way to ensure sorted order.