Call the gpart sorting routine, not twice the part sorting routine...

src/space.c

@@ -486,8 +486,8 @@ void space_rebuild(struct space *s, double cell_max, int verbose) {
 
 #endif
 
-  /* Sort the parts according to their cells. */
-  space_parts_sort(s, ind, nr_gparts, 0, s->nr_cells - 1, verbose);
+  /* Sort the gparts according to their cells. */
+  space_gparts_sort(s, ind, nr_gparts, 0, s->nr_cells - 1, verbose);
 
   /* Re-link the parts. */
   for (int k = 0; k < nr_gparts; k++)