--- a/mercurial/dirstatemap.py	Thu Sep 23 18:29:40 2021 +0200
+++ b/mercurial/dirstatemap.py	Tue Sep 28 13:43:14 2021 +0200
@@ -575,6 +575,8 @@
             elif possibly_dirty:
                 item = DirstateItem.new_possibly_dirty()
             else:
+                assert size is not None
+                assert mtime is not None
                 size = size & rangemask
                 mtime = mtime & rangemask
                 item = DirstateItem.new_normal(mode, size, mtime)