bitbake: cooker: Fix main loop starvation when parsing

When parsing, the parser isn't servicing the main loop so a Ctrl+C in the
UI won't be seen on the cooker/server side. Fix this by returning when queue
timeouts occur. This helps where there is a hung or slow parsing thread.

(Bitbake rev: a2cde38311a51112dca5e7bb4e7feaf4e6a281b3)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/cooker.py

@@ -2249,7 +2249,7 @@ class CookerParser(object):
                 result = self.result_queue.get(timeout=0.25)
             except queue.Empty:
                 empty = True
-                pass
+                yield None, None, None
             else:
                 empty = False
                 yield result
@@ -2266,6 +2266,10 @@ class CookerParser(object):
             if isinstance(result, BaseException):
                 # Turn exceptions back into exceptions
                 raise result
+            if parsed is None:
+                # Timeout, loop back through the main loop
+                return True
+
         except StopIteration:
             self.shutdown()
             return False