md5sums.txt is always output

[edbennett]

Even when the -m option is not passed, that file md5sums.txt is still created.

This is because the definition of the -m option uses action="store_true", default=False, while the check in the code uses options.md5 is not None.

Since options.md5 will only ever be True or False, it is always not None, so this check always passes.