dev-python/more-itertools: don't install .pytest_cache files

Commit 79489db15f changed the way tests
are run and resulted in .pytest_cache directories being installed in
site-packages/.
This will prevent those directories from being installed while still
fixing ImportMismatchError.

Bug: https://bugs.gentoo.org/661412
Package-Manager: Portage-2.3.43, Repoman-2.3.10

dev-python/more-itertools/more-itertools-4.2.0-r1.ebuild

@@ -37,7 +37,6 @@ python_compile_all() {
 
 python_test() {
 	# Avoid ImportMismatchError, see https://bugs.gentoo.org/661412
-	cd "${BUILD_DIR}/lib" || die
-	py.test --doctest-modules more_itertools \
+	pytest --doctest-modules "${BUILD_DIR}"/lib/more_itertools \
 		|| die "tests fail with ${EPYTHON}"
 }