incompatibility between \thepstart and the Memoir class

[Jean-Baptiste-Camps]

The current \thepstart definition causes an error with used with the memoir class :
\renewcommand{\thepstart}{{\bf@arabic\c@pstart}. }

The command \bf is not compatible with the Memoir class. Moreover, commands such as \bf or \it are deprecated and should no longer be used (see http://www.tex.ac.uk/cgi-bin/texfaq2html?label=2letterfontcmd). Instead, commands such as \bfseries should be used :
\renewcommand{\thepstart}{{\bfseries@arabic\c@pstart}. }
works just fine.