Use pylint's built-in checker to check for CRLF.

.pylintrc

@@ -4,7 +4,6 @@
 ignore=resources.py
 extension-pkg-whitelist=PyQt5,sip
 load-plugins=pylint_checkers.config,
-             pylint_checkers.crlf,
              pylint_checkers.modeline,
              pylint_checkers.openencoding,
              pylint_checkers.settrace

scripts/pylint_checkers/crlf.py

@@ -1,45 +0,0 @@
-# Copyright 2014-2015 Florian Bruhin (The Compiler) <mail@qutebrowser.org>
-# vim: ft=python fileencoding=utf-8 sts=4 sw=4 et:
-
-# This file is part of qutebrowser.
-#
-# qutebrowser is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# qutebrowser is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with qutebrowser.  If not, see <http://www.gnu.org/licenses/>.
-
-"""Checker for CRLF in files."""
-
-from pylint import interfaces, checkers
-
-
-class CrlfChecker(checkers.BaseChecker):
-
-    """Check for CRLF in files."""
-
-    __implements__ = interfaces.IRawChecker
-
-    name = 'crlf'
-    msgs = {'W9001': ('Uses CRLFs', 'crlf', None)}
-    options = ()
-    priority = -1
-
-    def process_module(self, node):
-        """Process the module."""
-        for (lineno, line) in enumerate(node.file_stream):
-            if b'\r\n' in line:
-                self.add_message('crlf', line=lineno)
-                return
-
-
-def register(linter):
-    """Register the checker."""
-    linter.register_checker(CrlfChecker(linter))

tox.ini

@@ -61,8 +61,8 @@ deps =
     six==1.9.0
 commands =
     {[testenv:mkvenv]commands}
-    {envdir}/bin/pylint scripts qutebrowser --rcfile=.pylintrc --output-format=colorized --reports=no
+    {envdir}/bin/pylint scripts qutebrowser --rcfile=.pylintrc --output-format=colorized --reports=no --expected-line-ending-format=LF
-    {envpython} scripts/run_pylint_on_tests.py --rcfile=.pylintrc --output-format=colorized --reports=no
+    {envpython} scripts/run_pylint_on_tests.py --rcfile=.pylintrc --output-format=colorized --reports=no --expected-line-ending-format=LF
 
 [testenv:pep257]
 skip_install = true