--- a/tests/test-diff-change.t	Wed May 23 00:25:29 2012 +0900
+++ b/tests/test-diff-change.t	Wed May 30 14:13:57 2012 -0500
@@ -29,6 +29,12 @@
   -first
   +second
 
+Test dumb revspecs (issue3474)
+
+  $ hg diff -r 2:2
+  $ hg diff -r "2 and 1"
+  abort: empty revision range
+  [255]
 
 Testing diff --change when merge: