When I create a simple project and add Execute shell task,
after save, the task contents are empty.
config.xml on the server is empty too:
When editing the config a second time, the contents are saved properly.
Each consecutive add of shell task requires a second edit.
When using inheritance plugin, there is no way to workaround the bug, since each edit creates new revision, and all shell tasks are empty.
I tested it on 1.563 and 1.564