Comment 6 for bug 967471

The wrong colors are what I meant in the last paragraph with libopenraw not being entirely painless yet.

The reason for why it worked before could be changes in libtiff assuming the library version changed between Ubuntu versions.
libtiff-3.9.5 apparently became a bit more strict regarding the TIFF layout than its predecessor and doesn't seem to make an assumption about missing or wrong TIFF settings anymore which made it work before.

This is likely going to stay this way as when I once tested it with libtiff-4.0 it wouldn't even load the preview from the CR2 but will cancel the image loading with an error message.