Yeah, commit b054ac3 now makes it so that CROTA2 is only updated if it's already there.  It won't be updated if a rotation matrix is provided, but it will be updated in the case of implicit specification of the rotation angle (when the user just wants to rotate the map to the correct orientation based on the CROTA2 keyword by calling `rotate()` with no arguments).

I don't think it needs to be a warning.