RawTherapee 5.4 Black and White convert results in colour cast

[heckflosse (Ingo Weyrich)]

@Morgan_Hardwood

And I suppose that as such, it is not possible to make R=G=B when using the a* and b* curve despite enabling the B&W tool.

Confirmed
If a* or b* curve is used the code to force R=G=B is not called.