remove pyutil dependency

[exarkun]

Fixes https://tahoe-lafs.org/trac/zfec/ticket/17

[sajith]

This looks good to me (ran tests locally, eye-balled substituted code in pyutils). I just have this nitpick/question about this line in tox.ini:

deps = .[test]

I was unable to find anything in Tox documentation about how expansion of .[test] works. I could sort of infer that it has something to do with the test dependencies from setup.py. Perhaps a note would help?

[sajith]

I was unable to find anything in Tox documentation about how expansion of .[test] works. I could sort of infer that it has something to do with the test dependencies from setup.py. Perhaps a note would help?

Eh, please feel free to ignore this. I finally figured out that where this is documented (pip and setuptools). Not knowing it was a matter of my unwillingness to learn stuff that I should have learned. :-)