Issue 6867 - Fix pytest 3.7.1 mock regression

tests/test_page_outputs.py

 import os
 import sys
 import runpy
 
 import mock
 import pytest
 import urllib2
 
 from .conftest import ROOTPATH
 from .utils import get_dir_contents, run_test_server
@@ skipping 13 matching lines @@
         # Remove the expected outputs that don't apply for this test type.
         if '@' in filename:
             del outputs[filename]
     return outputs.items()
 
 
 static_expected_outputs = get_expected_outputs('static')
 dynamic_expected_outputs = get_expected_outputs('dynamic')
 
 
-@mock.patch('cms.sources.FileSource.version', 1)
 @pytest.fixture(scope='session')
 def static_output(request, temp_site):
     static_out_path = os.path.join(temp_site, 'static_out')
     sys.argv = ['filler', temp_site, static_out_path]
-
-    runpy.run_module('cms.bin.generate_static_pages', run_name='__main__')
+    with mock.patch('cms.sources.FileSource.version', 1):
+        runpy.run_module('cms.bin.generate_static_pages', run_name='__main__')
     return static_out_path
 
 
 @pytest.fixture(scope='module')
 def dynamic_server(temp_site):
     with run_test_server(temp_site) as ts:
         yield ts
 
 
 @pytest.fixture(scope='session')
@@ skipping 11 matching lines @@
 
 @pytest.mark.parametrize('filename,expected_output', dynamic_expected_outputs)
 def test_dynamic(dynamic_server, filename, expected_output):
     response = urllib2.urlopen(dynamic_server + filename)
     assert expected_output == response.read().strip()
 
 
 def test_cache(output_pages):
     source = FileSource(os.path.join('test_site'))
     assert source.get_cache_dir() == os.path.join('test_site', 'cache')