Bring back tox-pip-version now that pglass/tox-pip-version#20 is fixed.
@@ -4,9 +4,8 @@ minversion = 3.2
# https://github.com/jaraco/skeleton/issues/6
tox_pip_extensions_ext_venv_update = true
# Ensure that a late version of pip is used even on tox-venv.
-# Disabled due to pglass/tox-pip-version#20.
requires =
-# tox-pip-version
+ tox-pip-version>=0.0.6
tox-venv
