Don't write bytecode when generating pydeps files.

Bug: 767620
Change-Id: I33072a124e7b487aeb97dba2b0c57d1daf3ea980
Reviewed-on: https://chromium-review.googlesource.com/705095
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: John Budorick <jbudorick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#507103}

PRESUBMIT.py

@@ -1984,8 +1984,11 @@ def DetermineIfStale(self, pydeps_path):
     import difflib
     old_pydeps_data = self._LoadFile(pydeps_path).splitlines()
     cmd = old_pydeps_data[1][1:].strip()
+    env = {
+      'PYTHONDONTWRITEBYTECODE': '1'
+    }
     new_pydeps_data = self._input_api.subprocess.check_output(
-        cmd  + ' --output ""', shell=True)
+        cmd  + ' --output ""', shell=True, env=env)
     old_contents = old_pydeps_data[2:]
     new_contents = new_pydeps_data.splitlines()[2:]
     if old_pydeps_data[2:] != new_pydeps_data.splitlines()[2:]:

PRESUBMIT_test.py

@@ -695,7 +695,7 @@ def testRelevantPyNoChange(self):
       MockAffectedFile('A.py', []),
     ]
 
-    def mock_check_output(cmd, shell=False):
+    def mock_check_output(cmd, shell=False, env=None):
       self.assertEqual('CMD A --output ""', cmd)
       return self.checker._file_cache['A.pydeps']
 
@@ -713,7 +713,7 @@ def testRelevantPyOneChange(self):
       MockAffectedFile('A.py', []),
     ]
 
-    def mock_check_output(cmd, shell=False):
+    def mock_check_output(cmd, shell=False, env=None):
       self.assertEqual('CMD A --output ""', cmd)
       return 'changed data'
 
@@ -732,7 +732,7 @@ def testRelevantPyTwoChanges(self):
       MockAffectedFile('C.py', []),
     ]
 
-    def mock_check_output(cmd, shell=False):
+    def mock_check_output(cmd, shell=False, env=None):
       return 'changed data'
 
     self.mock_input_api.subprocess.check_output = mock_check_output