colortbl: Overhang specs for `\cellcolor` not working

With the `colortbl` package, the optional overhang argument seems to be ignored when using `\cellcolor`. E.g., `\cellcolor{red}[0pt] content` prints `[0pt] content` into the corresponding table cell.

BTW, I'm not sure whether overhang specs are supposed to work with `\cellcolor`, but it isn't evident from the documentation that they shouldn't. 