bug#25890: `color-values` gives wrong value

[Eli Zaretskii]

> From: "mail@yo.eki.do" <mail@yo.eki.do>
> Date: Fri, 10 Mar 2017 05:23:35 +0000
> 
> I'd like to ask a question regarding to the commit 7b00e956.
> I quickly scanned the discussion here, but couldn't find any good reason for 
> changing the behavior of
> color-rgb-to-hex function without keeping backward compatibility;
> why the default value for digits-per-component is 4, not 2?

The default was changed to 4 to match how Emacs does color
calculations internally.  Using 2 will produce subtle bugs, like that
one which prompted that change.

> This change actually had impact on several packages including mode-icons, and 
> IMO keeping the original
> behavior is a better option.

I'm sorry to hear that, but you could still use the optional argument
to get back the original behavior, right?