update Travis settings

.travis.yml

@@ -20,7 +20,7 @@ install:
   - pip install --upgrade pip setuptools wheel
   - pip install --only-binary=numpy numpy
   - pip install -r requirements.txt
-  - pip install 'coverage>=4.0,<4.4' --force-reinstall # Upstream bug: https://bitbucket.org/ned/coveragepy/issues/578/incomplete-file-path-in-xml-report
+  - pip install 'coverage>=4.0,<4.4' --force-reinstall # Upstream bug: https://github.com/nedbat/coveragepy/issues/578
   
 before_script:
   - curl -L https://codeclimate.com/downloads/test-reporter/test-reporter-latest-linux-amd64 > ./cc-test-reporter