add one more branch assert

Author: vladak

opengrok-indexer/src/test/java/org/opengrok/indexer/history/MercurialRepositoryTest.java

@@ -516,6 +516,7 @@ void testBuildTagListOneMore() throws Exception {
 
         MercurialRepository hgRepo = (MercurialRepository) RepositoryFactory.getRepository(repositoryRoot);
         assertNotNull(hgRepo);
+        assertEquals("default", hgRepo.getBranch());
 
         // Add tag. Using double space on purpose to test the parsing of tags.
         final String newTagName = "foo  bar";