pyflakes warns about various errors, addressed here. For cls_cluster.py,
remove (unknown) sys.exit and replace through Exception, as sys.exit()
has the unwanted effect that the CI script would stop.  Instead, raise
an Exception that would show the problem in the HTML, and ensures that
the script runs until the end.

These are the warnings flagged by pyflakes.

    cls_cluster.py:297:4: undefined name 'sys'

    cls_containerize.py:39:1: 'subprocess' imported but unused
    cls_containerize.py:41:1: 'threading' imported but unused
    cls_containerize.py:43:1: 'multiprocessing.Process' imported but unused
    cls_containerize.py:43:1: 'multiprocessing.Lock' imported but unused
    cls_containerize.py:43:1: 'multiprocessing.SimpleQueue' imported but unused
    cls_containerize.py:49:1: 'cls_cluster as OC' imported but unused
    cls_containerize.py:50:1: redefinition of unused 'cls_cmd' from line 42

    cls_module.py:28:1: 'os' imported but unused
    cls_module.py:29:1: 'sys' imported but unused
    cls_module.py:34:1: 'subprocess' imported but unused
    cls_module.py:35:1: 'datetime.datetime' imported but unused
    cls_module.py:211:11: undefined name 'sshconnection'

    cls_oaicitest.py:37:1: 'pexpect' imported but unused
    cls_oaicitest.py:47:1: 'cls_cluster as OC' imported but unused
    cls_oaicitest.py:54:1: 'matplotlib.pyplot as plt' imported but unused
    cls_oaicitest.py:55:1: 'numpy as np' imported but unused

    cls_oai_html.py:34:1: 'sys' imported but unused
    cls_oai_html.py:41:1: 'multiprocessing.Process' imported but unused
    cls_oai_html.py:41:1: 'multiprocessing.Lock' imported but unused
    cls_oai_html.py:41:1: 'multiprocessing.SimpleQueue' imported but unused

    cls_physim.py:37:1: 'multiprocessing.SimpleQueue' imported but unused

    cls_static_code_analysis.py:39:1: 'time' imported but unused
    cls_static_code_analysis.py:40:1: 'multiprocessing.Process' imported but unused
    cls_static_code_analysis.py:40:1: 'multiprocessing.Lock' imported but unused
    cls_static_code_analysis.py:40:1: 'multiprocessing.SimpleQueue' imported but unused

    epc.py:41:1: 'multiprocessing.Process' imported but unused
    epc.py:41:1: 'multiprocessing.Lock' imported but unused
    epc.py:41:1: 'multiprocessing.SimpleQueue' imported but unused

    main.py:60:1: 'pexpect' imported but unused
    main.py:66:1: 'datetime' imported but unused
    main.py:68:1: redefinition of unused 'subprocess' from line 63
    main.py:70:1: 'multiprocessing.Process' imported but unused
    main.py:70:1: 'multiprocessing.Lock' imported but unused
    main.py:70:1: 'multiprocessing.SimpleQueue' imported but unused

    provideUniqueImageTag.py:2:1: 'os' imported but unused