Pass through PIP_UNSTABLE_FEATURE into Tox
@@ -11,7 +11,14 @@ pip = python {toxinidir}/tools/tox_pip.py
[testenv]
# Remove USERNAME once we drop PY2.
-passenv = CI GIT_SSL_CAINFO USERNAME HTTP_PROXY HTTPS_PROXY NO_PROXY
+passenv =
+ CI
+ GIT_SSL_CAINFO
+ USERNAME
+ HTTP_PROXY
+ HTTPS_PROXY
+ NO_PROXY
+ PIP_UNSTABLE_FEATURE
setenv =
# This is required in order to get UTF-8 output inside of the subprocesses
# that our tests use.
