diff -r 63e86fc9bfec -r 61ce70fd420e tests/test-empty-manifest-index.t
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test-empty-manifest-index.t	Tue Oct 12 19:43:51 2021 +0100
@@ -0,0 +1,23 @@
+Create a repo such that the changelog entry refers to a null manifest node:
+
+  $ hg init a
+  $ cd a
+  $ hg log
+  $ touch x
+  $ hg add x
+  $ hg commit -m "init"
+  $ hg rm x
+  $ hg commit -q --amend
+
+  $ wc -c < .hg/store/00manifest.i
+  0
+
+Make sure that the manifest can be read (and is empty):
+
+  $ hg --config rhg.on-unsupported=abort files -r .
+  [1]
+
+Test a null changelog rev, too:
+
+  $ hg --config rhg.on-unsupported=abort files -r 0000000000000000000000000000000000000000
+  [1]