cmdtest.py.in: Check for 'Traceback'
cmdtest.py.in: Check for 'Traceback'

We should never get an uncaught exception in the command line.  Always
check for it in the output.

Also, instead of decoding to a string everywhere we need it, we will decode
once before we return for `call`.

Signed-off-by: Tony Asleson <1ef2d381aa56d512126ddaacc29e68136e4fdf55@redhat.com>

tasleson/libstoragemgmt,tasleson/libstoragemgmt,tasleson/libstoragemgmt,libstorage/libstoragemgmt,libstorage/libstoragemgmt,tasleson/libstoragemgmt,tasleson/libstoragemgmt,libstorage/libstoragemgmt,libstorage/libstoragemgmt,libstorage/libstoragemgmt