Maybe just the pin needs to be removed

.travis.yml

@@ -12,7 +12,7 @@ env:
  - LC_ALL=C LC_CTYPE=C
 script:
  # avoid VersionConflict when newer version is required
- - pip install -U pytest flake8
+ - pip install -U pytest
 
  # Output the env, because the travis docs just can't be trusted
  - env

appveyor.yml

@@ -12,6 +12,5 @@ install:
 build: off
 
 test_script:
-  - "python -m pip install -U flake8"
   - "python bootstrap.py"
   - "python setup.py test"

setup.py

@@ -181,8 +181,6 @@ setup_params = dict(
     tests_require=[
         'setuptools[ssl]',
         'pytest-flake8',
-        # workaround for pytest-flake8 #7
-        'flake8<3dev',
         'pytest>=2.8',
     ] + (['mock'] if sys.version_info[:2] < (3, 3) else []),
     setup_requires=[