use python -m pip in test_wheels

python/perspective/scripts/test_wheels.sh

@@ -78,6 +78,10 @@ source ./bin/activate
 echo "${PYTHON_INTERPRETER} virtualenv activated"
 cd ..
 
+echo "Upgrading pip for ${PYTHON_INTERPRETER}..."
+${PYTHON_INTERPRETER} -m pip install --upgrade pip
+
+echo "Looking for wheels..."
 cd ${HERE}/../wheelhouse
 
 # Look for wheels based on Python version/platform
@@ -89,13 +93,15 @@ IFS=${SAVEIFS}
 
 for wheel in ${WHEELS_LIST}; do
     echo "Installing ${wheel}..."
-    pip install --force-reinstall ${wheel}
+    ${PYTHON_INTERPRETER} -m pip install --force-reinstall ${wheel}
 
     echo "-----------------------"
     echo "Testing ${wheel}"
 
     IS_LIBPSP=$(${PYTHON_INTERPRETER} -c "import perspective;print(perspective.is_libpsp())")
 
+    echo "-----------------------"
+
     if [ "${IS_LIBPSP}" != "True" ]; then
         echo "${wheel} failed to import with error: ${IS_LIBPSP}"
         echo "${VENV_DIR} has been preserved for debugging"