invoking hg diff --nodates --change 1:
diff -r 4bb65dda5db4 -r e9b286083166 file.txt
--- a/file.txt
+++ b/file.txt
@@ -1,1 +1,1 @@
-first
+second

invoking hg diff --nodates --change e9b286083166:
diff -r 4bb65dda5db4 -r e9b286083166 file.txt
--- a/file.txt
+++ b/file.txt
@@ -1,1 +1,1 @@
-first
+second

invoking hg diff --nodates --change 6:
diff -r e8a0797e73a6 -r aa9873050139 file.txt
--- a/file.txt
+++ b/file.txt
@@ -6,6 +6,6 @@
 5
 6
 7
-8
+y
 9
 10

EOF
