RefUpdateTest: Use try-with-resource for auto-closable types

Change-Id: I25c8db0e410aa2a4a53dc7d8863e4a6efefcf7cb
Signed-off-by: David Pursehouse <david.pursehouse@sonymobile.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/RefUpdateTest.java

@@ -558,13 +558,15 @@ public class RefUpdateTest extends SampleDataRepositoryTestCase {
 		assertEquals(ppid, db.resolve("refs/heads/master"));
 
 		// real test
-		RevCommit old = new RevWalk(db).parseCommit(ppid);
-		RefUpdate updateRef2 = db.updateRef("refs/heads/master");
-		updateRef2.setExpectedOldObjectId(old);
-		updateRef2.setNewObjectId(pid);
-		Result update2 = updateRef2.update();
-		assertEquals(Result.FAST_FORWARD, update2);
-		assertEquals(pid, db.resolve("refs/heads/master"));
+		try (RevWalk rw = new RevWalk(db)) {
+			RevCommit old = rw.parseCommit(ppid);
+			RefUpdate updateRef2 = db.updateRef("refs/heads/master");
+			updateRef2.setExpectedOldObjectId(old);
+			updateRef2.setNewObjectId(pid);
+			Result update2 = updateRef2.update();
+			assertEquals(Result.FAST_FORWARD, update2);
+			assertEquals(pid, db.resolve("refs/heads/master"));
+		}
 	}
 
 	/**
@@ -707,9 +709,10 @@ public class RefUpdateTest extends SampleDataRepositoryTestCase {
 
 		// Create new Repository instance, to reread caches and make sure our
 		// assumptions are persistent.
-		Repository ndb = new FileRepository(db.getDirectory());
-		assertEquals(rb2, ndb.resolve("refs/heads/new/name"));
-		assertNull(ndb.resolve("refs/heads/b"));
+		try (Repository ndb = new FileRepository(db.getDirectory())) {
+			assertEquals(rb2, ndb.resolve("refs/heads/new/name"));
+			assertNull(ndb.resolve("refs/heads/b"));
+		}
 	}
 
 	public void tryRenameWhenLocked(String toLock, String fromName,