sched: Avoid adding the same channel twice to the KIST pending list

This is the quick fix that is keeping the channel in PENDING state so if we
ever try to reschedule the same channel, it won't happened.

Fixes #24700

Signed-off-by: David Goulet <dgoulet@torproject.org>

changes/bug24700

@@ -0,0 +1,4 @@
+  o Minor bugfixes (scheduler, KIST):
+    - Avoid adding the same channel twice in the KIST scheduler pending list
+      wasting CPU cycles at handling the same channel twice. Fixes bug 24700;
+      bugfix on 0.3.2.1-alpha.

src/or/scheduler_kist.c

@@ -693,7 +693,6 @@ kist_scheduler_run(void)
        * after the scheduling loop is over. They can hopefully be taken care of
        * in the next scheduling round.
        */
-      chan->scheduler_state = SCHED_CHAN_WAITING_TO_WRITE;
       if (!to_readd) {
         to_readd = smartlist_new();
       }