tox >= 2.0 needs passenv in tox.ini, so that fakeroot can work

tox 2.x does not inherit environment vars by default.

tox.ini

@@ -5,6 +5,7 @@ envlist = py32, py33, py34
 # Change dir to avoid import problem
 changedir = docs
 commands = {envpython} -m borg.testsuite.run -bv []
+passenv = *  # fakeroot -u needs some env vars
 
 [testenv:py32]
 deps = mock