fix coverage reporter

Author: gaborbernat

tox.ini

@@ -35,8 +35,8 @@ source = src
          .tox/*/lib/python*/site-packages
          .tox/pypy*/site-packages
          .tox\*\Lib\site-packages
-         */virtualenv.py
-         *\virtualenv.py
+         */src
+         *\src
 
 [testenv:coverage]
 description = [run locally after tests]: combine coverage data and create report;
@@ -47,11 +47,11 @@ deps = {[testenv]deps}
 skip_install = True
 passenv = DIFF_AGAINST
 setenv = COVERAGE_FILE={toxworkdir}/.coverage
-commands = coverage erase
-           coverage combine
-           coverage report -m
-           coverage xml -o {toxworkdir}/coverage.xml
-           coverage html -d {toxworkdir}/htmlcov
+commands = coverage erase --rcfile="{toxinidir}/tox.ini"
+           coverage combine --rcfile="{toxinidir}/tox.ini"
+           coverage report -m --rcfile="{toxinidir}/tox.ini"
+           coverage xml -o {toxworkdir}/coverage.xml --rcfile="{toxinidir}/tox.ini"
+           coverage html -d {toxworkdir}/htmlcov --rcfile="{toxinidir}/tox.ini"
            diff-cover --compare-branch {env:DIFF_AGAINST:origin/master} {toxworkdir}/coverage.xml
 
 [testenv:cross_python2]