bitbake: build: Handle SystemExit in python tasks correctly

If a python task fails with sys.exit(), we currently see no TaskFailed event.
The high level code does detect the exit code and fail the task but it can
leave the UI inconsistent with log output.

Fix this be intercepting SystemExit explicitly. This makes python
task failures consistent with shell task failures.

(Bitbake rev: 9eee9fd4f2f96789ad2b037e74d561bdc1426856)

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

bitbake/lib/bb/build.py

@@ -694,7 +694,7 @@ def _exec_task(fn, task, d, quieterr):
         except bb.BBHandledException:
             event.fire(TaskFailed(task, fn, logfn, localdata, True), localdata)
             return 1
-        except Exception as exc:
+        except (Exception, SystemExit) as exc:
             if quieterr:
                 event.fire(TaskFailedSilent(task, fn, logfn, localdata), localdata)
             else: