Make sure coverage errors with PyPy are ignored

Author: rhpvorderman

tox.ini

@@ -10,8 +10,9 @@ passenv=
 commands =
     # Create HTML coverage report for humans and xml coverage report for external services.
     coverage run --source=isal -m py.test tests
-    coverage html
-    coverage xml
+    # Ignore errors during report generation. Pypy does not generate proper coverage reports.
+    coverage html -i
+    coverage xml -i
 
 [testenv:coverage]
 # Separate test environment for cython coverage.