Make Sequence Clip color space correction editable

So I received a mixdown of an edit, in logC. 

I overwrote the media colorspace in the source clip, making it rec709.

However, the edit included a few shots of archive material that were already rec709. 

Overriding the input color space for just these shots on sequence clip level in color management seems logical, but this is a fixed setting.

The workaround this is making a subclip and changing it there, but it would be more logical if I can just override the source colorspace for these few shots on sequence clip level in color management .