fix internal error with coverage 5. #72

.coveragerc

@@ -1,6 +1,7 @@
 [run]
 branch = True
 source = textile
+parallel = True
 
 [report]
 show_missing = True

.travis.yml

@@ -13,7 +13,7 @@ python:
 # command to install dependencies
 install:
   - imagesize=''
-  - pip install -U coveralls pytest pytest-cov 'coverage<5' codecov
+  - pip install -U coveralls pytest pytest-cov coverage codecov
   - if [[ $IMAGESIZE == true ]] ; then imagesize='[imagesize]' ; fi
   - pip install -e ".${imagesize}"
 # command to run tests