Ratchet down and simplify linting rules

Some cleanup of the flake8 config while fixing minor linting
violations previously ignored.

Change-Id: Ie56205248a8f296c06fb19c24080e4ac52f76228

.flake8

@@ -1,6 +1,5 @@
 [flake8]
-# E123, E125 skipped as they are invalid PEP-8.
-show-source = True
-ignore = E123,E125,E126,E129,E226,H,W503,W504,W605
-builtins = _
 exclude=.venv,.git,.nox,.tox,dist,doc,*lib/python*,*egg,build
+# E123, E125 and W503 are invalid per PEP-8; OpenStack's H rules don't apply
+ignore = E123,E125,H,W503
+show-source = True

engagement/stats.py

@@ -368,10 +368,10 @@ def main(verbose=0):
     argument = parse_command_line()
     if argument.startswith('record-'):
         mode = 'record'
-        argument = argument[len(mode)+1:]
+        argument = argument[len(mode) + 1:]
     elif argument.startswith('replay-'):
         mode = 'replay'
-        argument = argument[len(mode)+1:]
+        argument = argument[len(mode) + 1:]
     else:
         mode = 'live'
 
@@ -412,7 +412,7 @@ def main(verbose=0):
             # Offset additional pages by half the returned entry count to help
             # avoid missing changes due to pagination instability
             if new_changes and new_changes[-1].get('_more_changes', False):
-                offset += int(len(new_changes)/2)
+                offset += int(len(new_changes) / 2)
             else:
                 offset = -1
 

engagement/who-approves.py

@@ -95,7 +95,7 @@ group_path = 'a/groups/%s/members/?recursive&pp=0'
 projects_file = ('gitweb?p=openstack/governance.git;a=blob_plain;'
                  'f=reference/projects.yaml;hb=%s')
 ref_name = 'refs/heads/master'
-aprv_pattern = 'label-Workflow = .*\.\.\+1 group (.*)'
+aprv_pattern = r'label-Workflow = .*\.\.\+1 group (.*)'
 projects = requests.get(gerrit_url + projects_file % ref_name)
 projects.encoding = 'utf-8'  # Workaround for Gitweb encoding
 projects = yaml.safe_load(projects.text)