bitbake: server/process: fix sig handle

process.signal_received is a list for signum and not iterable,
change a suitable method to handle sig.

(Bitbake rev: bfc53b190bd2530c2bfcea0690127d7eff620f45)

Signed-off-by: Yang Xu <yang.xu@mediatek.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/server/process.py

@@ -860,11 +860,10 @@ class ConnectionWriter(object):
                 process.queue_signals = True
                 self._send(obj)
                 process.queue_signals = False
-                try:
-                    for sig in process.signal_received.pop():
-                        process.handle_sig(sig, None)
-                except IndexError:
-                    pass
+
+                while len(process.signal_received) > 0:
+                    sig = process.signal_received.pop()
+                    process.handle_sig(sig, None)
         else:
             self._send(obj)