dev-python/PyPubSub: Change working directory for test runner

The default pytest test runner doesn't find the test cases
unless it is run in the correct directory.

Closes: https://bugs.gentoo.org/916697
Signed-off-by: Moritz Brunner <moritz.brunner+gentoo@posteo.de>

dev-python/PyPubSub/PyPubSub-4.0.3.ebuild

@@ -28,8 +28,9 @@ BDEPEND="
 		dev-python/pytest[${PYTHON_USEDEP}]
 	)"
 
-python_test() {
-	py.test -v -v || die
-}
-
 distutils_enable_tests pytest
+
+python_test() {
+	cd tests/suite
+	distutils-r1_python_test
+}