Print rev number that failed to backport when running in non-interactive mode.

Change-Id: Ib9a27a69c4cebdf37c9e9bf4001633520debf3d6
diff --git a/backflip b/backflip
index fd8e012..f9a6253 100755
--- a/backflip
+++ b/backflip
@@ -138,6 +138,11 @@
     echo -e "INTERACTIVE MODE COMMAND LINE TO REPRODUCE AND/OR FIX THE ISSUE:"
     echo -e "$0 -v $VERSION -b $DEV_BRANCH -r $REF_BRANCH $RARGS"
     echo -e "${lines}"
+
+    if ! $INTERACTIVE; then
+	exec 1>&3 2>&4
+	echo -e "Failed to backport rev $REV"
+    fi
   fi
   exit $1
 }
@@ -164,6 +169,10 @@
   fi
 fi
 
+if ! $INTERACTIVE; then
+   exec 3>&1 4>&2
+fi
+
 # ==============================================================================
 # Check that all the requested backports are available
 # ==============================================================================