limit isort to lower version

run-tests.sh

@@ -8,7 +8,7 @@
 # details.
 
 pydocstyle invenio_theme_tugraz tests docs && \
-isort . -c --df && \
+isort -rc -c -df && \
 check-manifest --ignore ".travis-*" && \
 sphinx-build -qnNW docs docs/_build/html && \
 python setup.py test

setup.py

@@ -18,7 +18,7 @@ history = open('CHANGES.rst').read()
 tests_require = [
     'check-manifest>=0.25',
     'coverage>=4.0',
-    'isort>=5.0',
+    'isort>=4.3.3, <5.0.0',
     'pydocstyle>=2.0.0',
     'pytest-cov>=2.5.1',
     'pytest-pep8>=1.0.6',