\documentclass{article}
\usepackage{ifthen}
\usepackage[final,pdftex]{graphicx}
\newboolean{GraphicsDraft}
\setboolean{GraphicsDraft}{true}
\newcommand{\nograph}{%
\ifthenelse{\boolean{GraphicsDraft}}
{true}%
{false}%
}%nograph
\begin{document}
\includegraphics*[draft=\nograph]{pic} % This gives an error
%
\renewcommand\nograph{\ifGraphicsDraft true\else false\fi}
\includegraphics*[draft=\nograph]{pic} % This is OK
\end{document}
An ifthenelse is problematic whereas the \ifGraphicsDraft works
Am I doing something stupid or is this a real bug
\ifthenelse
works. – egreg Jul 18 '17 at 22:13