# Accessing the current color of a color series

The xcolor documentation clearly states that \color{foo} (or similar commands) should access the current color of the (previously defined) color series foo. However, the following MWE produces a black square for me instead of the expected blue one.

Is this a bug? Am I doing anything wrong?

\documentclass{article}

\usepackage{xcolor}

\begin{document}

\definecolorseries{foo}{rgb}{last}{blue}{red}
\resetcolorseries{foo}

\textcolor{foo}{\rule{1ex}{1ex}}

\end{document}


The slightly awkward syntax foo!! does what foo should do and can be used as a workaround.
I have investigated a bit further and discovered that the internal representation of the color (\\color@foo) is
\xcolor@{}{}{rgb}{0,0,1}