--- a/mercurial/debugcommands.py	Tue May 17 12:05:09 2022 +0100
+++ b/mercurial/debugcommands.py	Mon May 16 23:12:49 2022 +0100
@@ -1017,6 +1017,22 @@
 
 
 @command(
+    b'debugdirstateignorepatternshash',
+    [],
+    _(b''),
+)
+def debugdirstateignorepatternshash(ui, repo, **opts):
+    """show the hash of ignore patterns stored in dirstate if v2,
+    or nothing for dirstate-v2
+    """
+    if repo.dirstate._use_dirstate_v2:
+        docket = repo.dirstate._map.docket
+        hash_len = 20  # 160 bits for SHA-1
+        hash_bytes = docket.tree_metadata[-hash_len:]
+        ui.write(binascii.hexlify(hash_bytes) + b'\n')
+
+
+@command(
     b'debugdiscovery',
     [
         (b'', b'old', None, _(b'use old-style discovery')),