Try to get tox to use the wheelhouse too

.circleci/config.yml

@@ -94,6 +94,7 @@ jobs:
             sudo --set-home -u nobody /tmp/project/.circleci/setup-virtualenv.sh \
                 "/tmp/venv" \
                 "/tmp/project" \
+                "${WHEELHOUSE_PATH}" \
                 "${TAHOE_LAFS_TOX_ENVIRONMENT}" \
                 "${TAHOE_LAFS_TOX_ARGS}"
 

.circleci/setup-virtualenv.sh

@@ -13,12 +13,20 @@ shift
 PROJECT_ROOT="$1"
 shift
 
+# The filesystem location of the wheelhouse which we'll populate with wheels
+# for all of our dependencies.
+WHEELHOUSE_PATH="$1"
+shift
+
 TAHOE_LAFS_TOX_ENVIRONMENT=$1
 shift
 
 TAHOE_LAFS_TOX_ARGS=$1
 shift || :
 
+# Tell pip where it can find any existing wheels.
+export PIP_FIND_LINKS="file://${WHEELHOUSE_PATH}"
+
 # Get everything else installed in it, too.
 "${BOOTSTRAP_VENV}"/bin/tox \
      -c "${PROJECT_ROOT}"/tox.ini \