Merge branch 'sp/merge' (early part)

* 'sp/merge' (early part):
  Improve merge performance by avoiding in-index merges.

git-merge.sh

@@ -301,11 +301,16 @@ f,*)
 	;;
 ?,1,*,)
 	# We are not doing octopus, not fast forward, and have only
-	# one common.  See if it is really trivial.
+	# one common.
+	git-update-index --refresh 2>/dev/null
+	case " $use_strategies " in
+	*' recursive '*|*' recur '*)
+		: run merge later
+		;;
+	*)
+		# See if it is really trivial.
 		git var GIT_COMMITTER_IDENT >/dev/null || exit
-
 		echo "Trying really trivial in-index merge..."
-	git-update-index --refresh 2>/dev/null
 		if git-read-tree --trivial -m -u -v $common $head "$1" &&
 		   result_tree=$(git-write-tree)
 		then
@@ -319,6 +324,7 @@ f,*)
 			exit 0
 		fi
 		echo "Nope."
+	esac
 	;;
 *)
 	# An octopus.  If we can reach all the remote we are up to date.