When running with ZServer, TimerServer will be started by ZConfig
machinery, because ZServer comes with some ZConfig data types for server
factory which start servers.

One Zope 2, ZServer was imported from zopeschema:

https://github.com/zopefoundation/Zope/blob/2.13.30/src/Zope2/Startup/zopeschema.xml#L10

and ZConfig used the TimerServerFactory to create a TimerService.

On Zope 4, ZServer is not imported anymore in the new wsgischema:

https://github.com/zopefoundation/Zope/blob/4.6.3/src/Zope2/Startup/wsgischema.xml

so the ZConfig data type can not be used to create the server.

Instead of relying on ZServer's ZConfig, we create the server directly
from the startup script, the logic to attach to waitress is already here
and startup and factory just called create, so the only difference is
that we no longer use zope.conf to configure TimerService, but configure
from the script.

SlapOS profile also needs to be modified in order to not include ZConfig
bits for timerserver and to pass the timerserver interval in the wrapper
to this script.

Since https://github.com/zopefoundation/Zope/commit/2da2c2c28a8b21e78e8ef93aa17da926e3102c26
SERVER_PORT is assumed to be convertible to int.

The value of this port is not really supposed to be used because
TimerServer requests does not have a server (for example in CMFActivity
we recreate the initial request), so put a value of -1 to prevent
accidental use.

Only catch exceptions, we don't need a bare except here. In case of
exception, log the traceback instead of being silent.

This can happen if there is an error very early during publication.

we don't support negative quantity (it is better represented by an
inversion of source and destination), and this allows better support of
the smallest slice in ERP5, more especially in SupplyLine_asCellRange,
where the title of the cell is computed with the min and max being None
or not.

See slapos.core!307 (b7d5041e)

The real issue is probably in the launcher.js file, but it is more tricky to fix

See slapos.core!313 (b02b2bff)

These are clone of Computer and Computer Partition, but used for virtual
computing devices, unrelated to physical hardware.