fix logic https://trac.osgeo.org/grass/changeset/55847

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@55849 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/vector/Vlib/copy.c

@@ -90,12 +90,12 @@ int Vect_copy_map_lines_field(struct Map_info *In, int field,
         
         /* get type of first feature from input vector map */
         Vect_rewind(In);
+        Vect_set_constraint_type(In, GV_POINT | GV_LINES);
         type = Vect_read_next_line(In, NULL, NULL);
         if (!(type & (GV_POINTS | GV_LINES)))
             G_fatal_error(_("Unsupported feature type %d"), type);
             
         /* create feature table with given feature type */
-        Vect_set_constraint_type(In, GV_POINT | GV_LINES);
         Vect_write_line(Out, type, NULL, NULL);
     }