Add missing @Test annotation in RepositoryCacheTest

Change-Id: I25a9b294084f7b9769efa67001a4973647da4079
Signed-off-by: Hugo Arès <hugo.ares@ericsson.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/RepositoryCacheTest.java

@@ -195,6 +195,7 @@ public class RepositoryCacheTest extends RepositoryTestCase {
 		assertEquals(0, ((Repository) db).useCnt.get());
 	}
 
+	@Test
 	public void testRepositoryUnregisteringWhenClosing() throws Exception {
 		FileKey loc = FileKey.exact(db.getDirectory(), db.getFS());
 		Repository d2 = RepositoryCache.open(loc);