The current tox.ini and test_pytest_cov.py make assumptions about the location of various Python binaries on my system, which made it hard for me to run the tests. I think this changeset removes the hardcoded paths without losing anything, although it does mean you'll have to place Python binaries in the names expected by tox for the various python versions (i.e. "python2.6", "python2.7") on your shell PATH. Maybe you're willing to do this in exchange for having tests that others can run, too?
Oops, just realized this duplicates #4. I think the approach here for test_dist_missing_data is a little more robust than just skipping, although I can't get that test to pass no matter what I do (the string "coverage: failed slaves" never appears in the output).