Merge remote-tracking branch 'mgax/pytest'

diff --cc .travis.yml
index 316cdbe186d6f930a5103c2baf368fa160c1275d,4f61b3478e85f0539d51a72bd031864b38156dd7..a448705689a7b2f81472ad1b8d2e40b37945de44
--- 1/.travis.yml
--- 2/.travis.yml
+++ b/.travis.yml
@@@ -6,6 -6,7 +6,7 @@@ python
    - "pypy"
  
  install:
 -  - pip install pytz pytest
++  - pip install pytest
    - pip install --editable .
  
  script: make test