[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.
missing-dep-for-interpreter make => make | build-essential | dpkg-dev (usr/*/cubicweb/skeleton/debian/rules)
embedded-javascript-library usr/share/cubicweb/cubes/shared/data/jquery.js