diff -u ghc-6.12.3/libraries/gen_contents_index gen_contents_index
--- ghc-6.12.3/libraries/gen_contents_index	2010-11-05 10:28:02.000000000 +1000
+++ gen_contents_index	2010-11-05 10:20:37.000000000 +1000
@@ -22,5 +22,5 @@
     done
     ;;
-*)
+--batch)
     HADDOCK=/usr/bin/haddock
     # We don't want the GHC API to swamp the index
@@ -32,6 +32,9 @@
         HADDOCK_ARGS="$HADDOCK_ARGS $HADDOCK_ARG"
     done
     ;;
+*)
+    HADDOCK=/bin/true
+    tty -s && echo Run with '--batch' to index package haddock docs.
 esac
 
 # Now create the combined contents and index pages