Keep (revisited) comment from https://github.com/pytest-dev/pytest/commit/4d31ea831

testing/test_meta.py

@@ -1,3 +1,9 @@
+"""
+Test importing of all internal packages and modules.
+
+This ensures all internal packages can be imported without needing the pytest
+namespace being set, which is critical for the initialization of xdist.
+"""
 import pkgutil
 import subprocess
 import sys