--- a/tests/test-log.t Thu Feb 04 13:21:01 2021 -0800
+++ b/tests/test-log.t Thu Feb 04 13:32:11 2021 -0800
@@ -1966,6 +1966,26 @@
@@ -0,0 +1,1 @@
+b
+
+Test that diff.merge is respected (file b was added on one side and
+and therefore merged cleanly)
+
+ $ hg log -pr 3 --config diff.merge=yes
+ changeset: 3:8e07aafe1edc
+ tag: tip
+ parent: 2:b09be438c43a
+ parent: 1:925d80f479bb
+ user: test
+ date: Thu Jan 01 00:00:00 1970 +0000
+ summary: 3
+
+ diff -r 8e07aafe1edc a
+ --- a/a Thu Jan 01 00:00:00 1970 +0000
+ +++ b/a Thu Jan 01 00:00:00 1970 +0000
+ @@ -1,1 +1,1 @@
+ -b
+ +c
+
$ cd ..
'hg log -r rev fn' when last(filelog(fn)) != rev