Fall back to legacy resolver in pip. Workaround for pypa/pip#9143.

jaraco · jaraco · commit 7d3f9cb5239e · 2021-11-08T17:21:04.000-05:00
diff --git a/tox.ini b/tox.ini
@@ -12,6 +12,9 @@ commands =
 	pytest {posargs}
 usedevelop = True
 extras = testing
+setenv =
+	# workaround pypa/pip#9143
+	PIP_USE_DEPRECATED=legacy-resolver
 
 [testenv:docs]
 extras =
