Add missing 'return False' to the SystemExit handler in runAsyncCommand

(Bitbake rev: 966490c555cbdc09f52e1dcc68d3772c28ad9cee)

Signed-off-by: Chris Larson <chris_larson@mentor.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>

bitbake/lib/bb/command.py

@@ -98,6 +98,7 @@ class Command:
                 self.finishAsyncCommand(arg)
             else:
                 self.finishAsyncCommand("Exited with %s" % arg)
+            return False
         except Exception:
             import traceback
             self.finishAsyncCommand(traceback.format_exc())