`single` option leads to wrong behavior of `\acp` if the acronym is only used once

Issue #93 resolved
Anonymous created an issue

The \acp macro doesn't create the plural form of the acronym if the acronym is only used once, the plural isn't set up using long-plural-form, and the single option is given as package option. The below code reproduces the misbehavior.

\documentclass[]{article}

\usepackage[single]{acro}
\DeclareAcronym{HMM}{%
    short=HMM,
    long=Hidden-Markov-Modell
}
\DeclareAcronym{HMM2}{%
    short=HMM,
    long=Hidden-Markov-Modell,
    long-plural-form=Hidden-Markov-Modells
}
\DeclareAcronym{PCA}{%
    short=PCA,
    long=Principle-Component-Analysis
}


\begin{document}
\noindent%
\acp{HMM} -- \emph{the plural form is not used}\\
\acp{HMM2} -- \emph{the plural form is used}\\
\acp{PCA} -- \emph{the plural form is used}\\
\ac{PCA}
\end{document}