Description of problem:
With the recent addition of unified way to refer to installation media (see Bug 488540) it becomes even more useful to have a unified way to handle update images.

Currently it seems that in case of ks=... path being incorrect, CD installation will automagically check for /updates directory for updates.img etc but this does not happen with, e.g., USB installations. This unification between CD/USB/DVD/SD/etc would be highly beneficial as scripting to create kickstart files etc becomes much easier and with a large set of users and systems it is impossible to know all the combinations they are used beforehand.

One use case example: with a customized install image with different profiles, some profiles supply a valid ks=... path and proceed as usual. Some profiles could provide knowingly an invalid ks=... path and thus check for update images in /updates directory which would then do something appropriate for those install targets. As said, this already can be done with CD installations but not with USB.