[l2h] \providecommand acting like \renewcommand in l2h

[Julius Orion Smith III]

The following test program illustrates an inconsistency between l2h and latex:
---
% test.tex:
\documentclass{article}
\newcommand{\color}{black}
\providecommand{\color}{white}
\begin{document}
I am \color. % latex prints 'black', l2h prints 'white'.
\end{document}
---

Julius