This would remove the ide-cd module, which has been deprecated for some time.

Rationale:

udev's cdrom handling have for a long time not dealt with drives using this module. We have a rule to partially compensate for this (it puts cdrom drives using the legacy module in the 'optical' group). However, there are many other features in udev's cdrom handling that we don't support.

I don't like supporting things half-way. We should either make upstream support legacy ide-cd properly, or we should remove ide-cd altogether.

I asked Kay (upstream) about this, and he told me that the new sr module supports all the drives that ide-cd did:

[14:12] <tomegun> kay: speaking of cdrom's i have been meaining to ask: i noticed that there is no longer support for legacy (ide) cdrom's in the upstream cdrom rules. we still have them in Arch,but i want to kill them (or move them upstream if they cannot be killed). is it known that ide-cdrom is never needed anymore? i know it is marked as depreecated, but i see it is shipped by e.g. fedora, so wonder if some hw still needs it?
[14:36] <kay> tomegun: it's dead. will not come back
[14:37] <kay> tomegun: disable it in the kernel
[14:38] <tomegun> ok, so I assume all hardware is supported by the new sr module?
[14:41] <kay> tomegun: yeah, it is since very long. there was some old powermac stuff missing, but long ago

I guess the worst case scenario if we disable this is that we find a bug in sr, which will either get fixed in sr, or the legacy cdrom support will get added back to udev.