Consider the following MWE:
\documentclass{article}
\usepackage{pstricks}
\begin{document}
A
\end{document}
It produces the error
Runaway argument?
] {pgffor.code.tex}
! Paragraph ended before \ProvidesPackageRCS@i was complete.
<to be read again>
\par
l.11
How do I fix this?
:-)\def\ProvidesPackageRCS{\@ifnextchar[\ProvidesPackageRCS@i{\ProvidesPackageRCS@i[] }}%$by\def\ProvidesPackageRCS#1{}