Restore DOCROOT setting after each test run

Otherwise this can fire sideeffects which might make test_builds fail, but
only when another RTDTestCase has run before it.

Author: gregmuellegger

readthedocs/rtd_tests/base.py

@@ -12,6 +12,7 @@
 
 class RTDTestCase(TestCase):
     def setUp(self):
+        self.original_DOCROOT = settings.DOCROOT
         self.cwd = os.path.dirname(__file__)
         self.build_dir = os.path.join(self.cwd, 'builds')
         log.info("build dir: %s" % self.build_dir)
@@ -21,6 +22,7 @@ def setUp(self):
 
     def tearDown(self):
         shutil.rmtree(self.build_dir)
+        settings.DOCROOT = self.original_DOCROOT
 
 
 @patch('readthedocs.projects.views.private.trigger_build', lambda x, basic: None)