https://github.com/jaraco/backports.entry_points_selectable/pull/8

--- backports.entry_points_selectable-1.3.0/tox.ini.orig
+++ backports.entry_points_selectable-1.3.0/tox.ini
@@ -4,7 +4,7 @@
 setenv =
 	PYTHONWARNDEFAULTENCODING = 1
 commands =
-	pytest {posargs}
+	python -m pytest {posargs}
 usedevelop = True
 extras =
 	testing