put the tox installation near other software installation

.circleci/create-virtualenv.sh

@@ -47,3 +47,7 @@ export PIP_FIND_LINKS="file://${WHEELHOUSE_PATH}"
 # above, it may still not be able to get us a compatible version unless we
 # explicitly ask for one.
 "${PIP}" install --upgrade setuptools==44.0.0 wheel
+
+# Just about every user of this image wants to use tox from the bootstrap
+# virtualenv so go ahead and install it now.
+"${PIP}" install "tox~=3.0"

.circleci/populate-wheelhouse.sh

@@ -31,7 +31,3 @@ LANG="en_US.UTF-8" "${PIP}" \
     --wheel-dir "${WHEELHOUSE_PATH}" \
     "${PROJECT_ROOT}"[testenv] \
     "${PROJECT_ROOT}"[test]
-
-# Put tox right into the bootstrap environment because everyone is going to
-# need to use it.
-"${PIP}" install "tox~=3.0"

.circleci/setup-virtualenv.sh

@@ -28,10 +28,6 @@ shift || :
 export PIP_FIND_LINKS="file://${WHEELHOUSE_PATH}"
 export PIP_NO_INDEX="1"
 
-# Get tox inside the bootstrap virtualenv since we use tox to manage the rest
-# of the environment.
-"${BOOTSTRAP_VENV}"/bin/pip install tox
-
 # Get everything else installed in it, too.
 "${BOOTSTRAP_VENV}"/bin/tox \
      -c "${PROJECT_ROOT}"/tox.ini \