osmo_ctrl.py: properly ignore out-of-order traps

Sometimes when we set variable we might receive arbitrary number of TRAP
messages before we get SET_REPLY. Those could be either separate
messages or combined together with SET_REPLY depending on tcp buffering
at server side. Let's handle this gracefully by skipping over all TRAP
messages.

An example command which often triggers this behavior:
./osmo_ctrl.py -s -d 127.0.0.1 -p 4249 bts.0.location (date +%s)",fix2d,1,2,3"

Change-Id: Ia6de02c2f13a56f0381c97a9ab02c6c7a31cc32f
Related: SYS#4399

scripts/osmo_ctrl.py

@@ -41,7 +41,13 @@ def do_set_get(sck, var, value = None):
         _leftovers(sck, socket.MSG_DONTWAIT)
         (r, c) = Ctrl().cmd(var, value)
         sck.send(c)
-        ret = sck.recv(4096)
+        while True:
+                ret = sck.recv(4096)
+                # handle multiple messages, ignore TRAPs
+                ret = Ctrl().skip_traps(ret)
+                if ret != None:
+                    (i, k, v) = Ctrl().parse(ret)
+                    break;
         return (Ctrl().rem_header(ret),) + Ctrl().verify(ret, r, var, value)
 
 def set_var(sck, var, val):