Code review comment for lp:~kenseehart/phatch/PGM_bugfix_472978_test

Also please fix these PEP8 issues:

PGM_bugfix_472978_test/tests$ ./run_pep8_test.py
../tests/run_acceptance_test.py:252:1: W291 trailing whitespace

^
1
../tests/test_suite/utils.py:93:24: E261 at least two spaces before inline comment
        'pgm': ['ppm'], # PIL bug: PIL saves greyscale PPM as PGM
                       ^
../tests/test_suite/utils.py:110:11: E225 missing whitespace around operator
    if ext!=t and ext not in altext.get(t, []):
          ^
2