parsers: remove unreachable and invalid code in index_ancestors

The function normally returns a list. Returning a single element instead of a
list with one element would be weird.

mercurial/parsers.c

@@ -1529,10 +1529,6 b' static PyObject *index_ancestors(indexOb'
 		ret = gca;
 		Py_INCREF(gca);
 	}
-	else if (PyList_GET_SIZE(gca) == 1) {
-		ret = PyList_GET_ITEM(gca, 0);
-		Py_INCREF(ret);
-	}
 	else ret = find_deepest(self, gca);
 
 done: