bitbake: hob: don't show error dialog for errors during building

During building we already report errors in a special tab and
indicate when the build has failed; bringing up a dialog was a
regression introduced in bitbake revision
5bab81b124087d63d6eb62a861e1241714fcd483.

Fixes [YOCTO #3151].

(Bitbake rev: cf0a67d62f631aa48d1afc3fbdd0f73995b1c401)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/ui/crumbs/hobeventhandler.py

@@ -183,10 +183,11 @@ class HobHandler(gobject.GObject):
             self.emit("sanity-failed", event._msg)
 
         elif isinstance(event, logging.LogRecord):
-            if event.levelno >= logging.ERROR:
-                formatter = bb.msg.BBLogFormatter()
-                msg = formatter.format(event)
-                self.error_msg += msg + '\n'
+            if not self.building:
+                if event.levelno >= logging.ERROR:
+                    formatter = bb.msg.BBLogFormatter()
+                    msg = formatter.format(event)
+                    self.error_msg += msg + '\n'
 
         elif isinstance(event, bb.event.TargetsTreeGenerated):
             self.current_phase = "data generation"