FanoutBucket: Create ObjectInserter.Formatter in try-with-resource

To prevent potential resource leak.

Change-Id: Ife09be2822bc476199f10da8d1eb7ccc8da05b79
Signed-off-by: David Pursehouse <david.pursehouse@sonymobile.com>

org.eclipse.jgit/src/org/eclipse/jgit/notes/FanoutBucket.java

@@ -260,8 +260,8 @@ class FanoutBucket extends InMemoryNoteBucket {
 	}
 
 	ObjectId getTreeId() {
-		try {
-			return new ObjectInserter.Formatter().idFor(build(false, null));
+		try (ObjectInserter.Formatter f = new ObjectInserter.Formatter()) {
+			return f.idFor(build(false, null));
 		} catch (IOException e) {
 			// should never happen as we are not inserting
 			throw new RuntimeException(e);