autostyle=once doesn't honor babel's main=⟨language⟩

[dbitouze]

According to the documentation, the autostyle=once option controls multilingual support by only adapting the style once so that it matches the main language of the document.

This does work if the main language is just the last listed one, as shown by the following MCE:

\documentclass[french,english]{article}
\usepackage[T1]{fontenc}
\usepackage[autostyle=once]{csquotes}
\usepackage{babel}

\begin{document}
\section{Default}
\enquote{Very interesting quote.}

\selectlanguage{french}
\section{French}
\enquote{Une très intéressante citation.}

\selectlanguage{english}
\section{English}
\enquote{Very interesting quote.}
\end{document}

But this doesn't work if the main language is stipulated through the babel's main=⟨language⟩ option, as shown by the following MCE:

\documentclass[french,main=english]{article}
\usepackage[T1]{fontenc}
\usepackage[autostyle=once]{csquotes}
\usepackage{babel}

\begin{document}
\section{Default}
\enquote{Very interesting quote.}

\selectlanguage{french}
\section{French}
\enquote{Une très intéressante citation.}

\selectlanguage{english}
\section{English}
\enquote{Very interesting quote.}
\end{document}

Interestingly, the babel's main=⟨language⟩ option is honored by the autostyle=true option

[dbitouze]

Sorry for the noise: babel's main=⟨language⟩ doesn't work at the \documentclass' level, but only at the \usepackage{babel}'s level.