Merge branch 'jc/pull' into next

* jc/pull:
  git-pull: reword "impossible to fast-forward" message.
  git-pull: further safety while on tracking branch.

git-pull.sh

@@ -55,9 +55,17 @@ then
 	# First update the working tree to match $curr_head.
 
 	echo >&2 "Warning: fetch updated the current branch head."
-	echo >&2 "Warning: fast forwarding your working tree."
+	echo >&2 "Warning: fast forwarding your working tree from"
+	echo >&2 "Warning: $orig_head commit."
+	git-update-index --refresh 2>/dev/null
 	git-read-tree -u -m "$orig_head" "$curr_head" ||
-		die "You need to first update your working tree."
+		die 'Cannot fast-forward your working tree.
+After making sure that you saved anything precious from
+$ git diff '$orig_head'
+output, run
+$ git reset --hard
+to recover.'
+
 fi
 
 merge_head=$(sed -e '/	not-for-merge	/d' \