I see doing a hotfix (or 1.5.1 or whatever) now as the only proper solution to this problem. Since renderfarms, as previously stated, won't install daily builds for sure, what happens is that now a bunch of users have a pile of scenes rendering incorrectly. Those users will have to wait a long time (which is mostly not an option) to be able to render them properly again. In the meantime, a lot of users will create a lot of new scenes which will, when 1.6 comes out, render incorrectly all over again. I just don't see how that works for anyone.
Best to address the issue while it's still fresh and not a lot of damage done, give everyone a heads up to install the hypothetical hotfix ASAP, and get it over with.
And it would be nice, at least, if the last daily build with the old colormapping was still available in dropbox. -.-