Revert "run_checks: Run pep257 via subprocess."

This reverts commit 380537d49c.

Conflicts:
	scripts/run_checks.py

This is needed because it seems pep257 doesn't install a binary on Windows.

scripts/run_checks.py

@@ -102,6 +102,27 @@ def run(name, target=None, print_version=False):
     return status
 
 
+def check_pep257(target):
+    """Run pep257 checker with args passed."""
+    # pylint: disable=assignment-from-no-return,no-member
+    args = _get_args('pep257')
+    sys.argv = ['pep257', target]
+    if args is not None:
+        sys.argv += args
+    try:
+        if hasattr(pep257, 'run_pep257'):
+            # newer pep257 versions
+            status = pep257.run_pep257()
+        else:
+            # older pep257 versions
+            status = pep257.main(*pep257.parse_options())
+        print()
+        return status
+    except Exception:
+        traceback.print_exc()
+        return None
+
+
 def check_unittest():
     """Run the unittest checker."""
     suite = unittest.TestLoader().discover('.')
@@ -231,7 +252,7 @@ def _get_checkers(args):
     # "Dynamic" checkers which exist once for each target.
     for target in config.get('DEFAULT', 'targets').split(','):
         checkers[target] = collections.OrderedDict([
-            ('pep257', functools.partial(run, 'pep257', target, args.version)),
+            ('pep257', functools.partial(check_pep257, target)),
             ('flake8', functools.partial(run, 'flake8', target, args.version)),
             ('vcs', functools.partial(check_vcs_conflict, target)),
             ('pylint', functools.partial(run, 'pylint', target, args.version)),