scoped \href arguments to avoid leaking color

[dginev]

I stumbled onto a simple color leakage arxiv report yesterday and found a quick fix.

But I am also a little unsatisfied by how specific the fix is - it only contains one macro, rather than all possible cases where this containment may be needed. But I am not sure which cases those are.

So for now I'm offering the quick fix for consideration. And adding a test.

Minimal example reproducing the issue:

\documentclass{article}
\usepackage{hyperref}
\usepackage{xcolor}
\begin{document}
A link: \href{https://example.com}{\color{blue}here}.

\section{Color should not leak into this heading}
This text should be black.

\end{document}