Don't count vendored code into coverage

Author: agronholm

setup.cfg

@@ -53,11 +53,12 @@ distutils.commands =
     bdist_wheel = wheel.bdist_wheel:bdist_wheel
 
 [tool:pytest]
-addopts = --cov=wheel
+addopts = --cov --cov-config=setup.cfg
 testpaths = tests
 
 [coverage:run]
 source = wheel
+omit = */vendored/*
 
 [coverage:report]
 show_missing = true