[server] Exit quickly when a looping task is registered in maintenance mode
In such cases the repository will not have a scheduler on purpose because the
repository will not be kept running and will quickly shutdown after migration
so that it's undesirable to have looping tasks being executed.
Document: cubicweb-doc
Title: CubicWeb Documentation
Author: Logilab
Abstract: Some base documentation for CubicWeb users and developpers
Section: Apps/Programming
Format: HTML
Index: /usr/share/doc/python-cubicweb-documentation/html/index.html
Files: /usr/share/doc/python-cubicweb-documentation/html/*