WIP: fix relative path finding when parent.path == self.path

Author: RonnyPfannschmidt

src/_pytest/nodes.py

@@ -536,9 +536,9 @@ def __init__(
     ) -> None:
         path, fspath = _imply_path(path, fspath=fspath)
         name = fspath.basename
-        if parent is not None:
+        if parent is not None and parent.path != path:
             try:
-                rel = Path(fspath).relative_to(parent.path)
+                rel = path.relative_to(parent.path)
             except ValueError:
                 pass
             else: