[PATCH] progress: Ensure missing start event is fired

[Richard Purdie <richard.purdie@linuxfoundation.org>]

The init function of the parent class fires a progress event for 0
progress rather than a start event. UI code was assuming that progress
events should always have a start event first. This change ensures that
the start event is correctly generated.

This fixes crashes that were seen in knotty in some configurations.

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

diff --git a/bitbake/lib/bb/progress.py b/bitbake/lib/bb/progress.py
index 4941776..ee6b953 100644
--- a/bitbake/lib/bb/progress.py
+++ b/bitbake/lib/bb/progress.py
@@ -209,6 +209,9 @@ class MultiStageProcessProgressReporter(MultiStageProgressReporter):
         bb.event.fire(bb.event.ProcessStarted(self._processname, 100), self._data)
 
     def _fire_progress(self, taskprogress):
+        if taskprogress == 0:
+            self.start()
+            return
         bb.event.fire(bb.event.ProcessProgress(self._processname, taskprogress), self._data)
 
     def finish(self):