PYTHON-2431 Fix MONGODB-AWS auth tests on macOS

Author: ShaneHarvey

.evergreen/config.yml

@@ -492,7 +492,7 @@ functions:
         script: |
           ${PREPARE_SHELL}
           # The aws_e2e_assume_role script requires python3 with boto3.
-          virtualenv -p ${python3_binary} mongovenv
+          ${python3_binary} -m venv mongovenv
           if [ "Windows_NT" = "$OS" ]; then
             . mongovenv/Scripts/activate
           else

.evergreen/run-mongodb-aws-test.sh

@@ -3,6 +3,9 @@
 set -o xtrace
 set -o errexit  # Exit the script with error if any of the commands fail
 
+# Get access to createvirtualenv.
+. .evergreen/utils.sh
+
 ############################################
 #            Main Program                  #
 ############################################
@@ -39,8 +42,6 @@ fi
 # show test output
 set -x
 
-VIRTUALENV=$(command -v virtualenv)
-
 authtest () {
     if [ "Windows_NT" = "$OS" ]; then
       PYTHON=$(cygpath -m $PYTHON)
@@ -49,7 +50,7 @@ authtest () {
     echo "Running MONGODB-AWS authentication tests with $PYTHON"
     $PYTHON --version
 
-    $VIRTUALENV -p $PYTHON --system-site-packages --never-download venvaws
+    createvirtualenv $PYTHON venvaws
     if [ "Windows_NT" = "$OS" ]; then
       . venvaws/Scripts/activate
     else

.evergreen/utils.sh

@@ -8,14 +8,16 @@ createvirtualenv () {
     PYTHON=$1
     VENVPATH=$2
     if $PYTHON -m virtualenv --version; then
-        VIRTUALENV="$PYTHON -m virtualenv"
+        VIRTUALENV="$PYTHON -m virtualenv --never-download"
+    elif $PYTHON -m venv -h >/dev/null; then
+        VIRTUALENV="$PYTHON -m venv"
     elif command -v virtualenv; then
-        VIRTUALENV="$(command -v virtualenv) -p $PYTHON"
+        VIRTUALENV="$(command -v virtualenv) -p $PYTHON --never-download"
     else
         echo "Cannot test without virtualenv"
         exit 1
     fi
-    $VIRTUALENV --system-site-packages --never-download $VENVPATH
+    $VIRTUALENV --system-site-packages $VENVPATH
     if [ "Windows_NT" = "$OS" ]; then
         . $VENVPATH/Scripts/activate
     else