CleanCommandTest: Open Repository in try-with-resource

Change-Id: If87cb729432ae711a2e7cfd08d288d7fec3f6de2
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/api/CleanCommandTest.java

@@ -240,8 +240,9 @@ public class CleanCommandTest extends RepositoryTestCase {
 		command.setPath(path);
 		String uri = db.getDirectory().toURI().toString();
 		command.setURI(uri);
-		Repository repo = command.call();
-		repo.close();
+		try (Repository repo = command.call()) {
+			// Unused
+		}
 
 		Status beforeCleanStatus = git.status().call();
 		assertTrue(beforeCleanStatus.getAdded().contains(DOT_GIT_MODULES));