Avoid soft-deprecated pathlist ini type on pytest>=7

This allows the test suite to succeed with the legacypath plugin
blocked.

Fix #722.

src/xdist/looponfail.py

@@ -38,7 +38,7 @@ def pytest_cmdline_main(config):
 
 def looponfail_main(config):
     remotecontrol = RemoteControl(config)
-    rootdirs = config.getini("looponfailroots")
+    rootdirs = [py.path.local(root) for root in config.getini("looponfailroots")]
     statrecorder = StatRecorder(rootdirs)
     try:
         while 1: