--- a/mercurial/commands.py	Wed Dec 23 16:22:20 2015 -0800
+++ b/mercurial/commands.py	Thu Dec 17 14:56:14 2015 +0000
@@ -330,6 +330,9 @@
     This command is useful for discovering when a change was made and
     by whom.
 
+    If you include --file, --user, or --date, the revision number is
+    suppressed unless you also include --number.
+
     Without the -a/--text option, annotate will avoid processing files
     it detects as binary. With -a, annotate will annotate the file
     anyway, although the results will probably be neither useful