Revert "Remove an erroneous 0.5 in compute_weighted_bandwidths()"

This reverts commit 01e984870a7e1db2722e85fe43af7bcb4755c2d4.

changes/bug23318

@@ -1,7 +0,0 @@
-  o Minor bugfixes (path selection):
-    - When selecting relays by bandwidth, avoid a rounding error that
-      could sometimes cause load to be imbalanced incorrectly. Previously,
-      we would always round upwards; now, we round towards the nearest
-      integer.  This had the biggest effect when a relay's weight adjustments
-      should have given it weight 0, but it got weight 1 instead.
-      Fixes bug 23318; bugfix on 0.2.4.3-alpha.

src/or/routerlist.c

@@ -2706,7 +2706,7 @@ compute_weighted_bandwidths(const smartlist_t *sl,
       final_weight = weight*this_bw;
     }
 
-    bandwidths[node_sl_idx] = final_weight;
+    bandwidths[node_sl_idx] = final_weight + 0.5;
   } SMARTLIST_FOREACH_END(node);
 
   log_debug(LD_CIRC, "Generated weighted bandwidths for rule %s based "