Changed invocation of muatation test in CI to bash script to use virtualenv

etc/ci/buildbot_steps.yml

@@ -68,7 +68,7 @@ linux-rel-nogate:
   - ./mach clean-nightlies --keep 3 --force
   - ./mach build --release
   - python ./etc/ci/chaos_monkey_test.py
-  - python ./etc/ci/mutation_test.py
+  - bash ./etc/ci/mutation_test.sh
 
 mac-rel-intermittent:
   - ./mach clean-nightlies --keep 3 --force

etc/ci/mutation_test.py

@@ -1,15 +0,0 @@
-# Copyright 2013 The Servo Project Developers. See the COPYRIGHT
-# file at the top-level directory of this distribution.
-#
-# Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-# http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-# <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-# option. This file may not be copied, modified, or distributed
-# except according to those terms.
-
-import subprocess
-import sys
-
-mutation_path = 'components/script/dom'
-status = subprocess.call('python python/servo/mutation/init.py %s' % mutation_path, shell=True)
-sys.exit(status)

etc/ci/mutation_test.sh

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+set -o errexit
+set -o nounset
+set -o pipefail
+
+source python/_virtualenv/bin/activate
+python python/servo/mutation/init.py components/script/dom