flake8: Add flake8-string-format plugin.

string format checker, plugin for flake8
https://pypi.python.org/pypi/flake8-string-format/

qutebrowser/misc/savemanager.py

@@ -86,9 +86,9 @@ class Saveable:
                 (not config.get(*self._config_opt)) and
                 (not explicit) and (not force)):
             if not silent:
-                log.save.debug("Not saving {} because autosaving has been "
+                log.save.debug("Not saving {name} because autosaving has been "
                                "disabled by {cfg[0]} -> {cfg[1]}.".format(
-                                   self._name, cfg=self._config_opt))
+                                   name=self._name, cfg=self._config_opt))
             return
         do_save = self._dirty or (self._save_on_exit and is_exit) or force
         if not silent:

setup.cfg

@@ -18,11 +18,15 @@ exclude = .venv,.hypothesis,.git,__pycache__,resources.py
 #       being concatenated is parenthesize
 # L207: pass is only necessary in non-optional suites containing no other
 #       statements.
+# P101: format string does contain unindexed parameters
+# P102: docstring does contain unindexed parameters
+# P103: other string does contain unindexed parameters
 ignore =
     E128,E226,E265,E501,E402,E266,
     F401,
     N802,
-    L101,L102,L103,L201,L202,L203,L204,L207
+    L101,L102,L103,L201,L202,L203,L204,L207,
+    P101,P102,P103
 max-complexity = 12
 putty-ignore =
     /# pylint: disable=invalid-name/ : +N801,N806

tox.ini

@@ -161,6 +161,7 @@ deps =
     mccabe==0.3.1
     pep8==1.7.0
     pyflakes==1.0.0
+    flake8-string-format==0.2.1
 commands =
     {envpython} -m flake8