How to insert math with curly brackets into tikz decoration text along path?

I was going to write along an arc some math expression with curly brackets. Somehow the following snippet causes pdflatex to freeze.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{decorations}
\usetikzlibrary{decorations.text}

\begin{document}

\begin{tikzpicture}

\draw[->,blue,
postaction={decorate,decoration={text along path, raise=4pt,
text={ $\{ hello \}${} },text color=blue,
text align={align=center}}}] (0,5) arc (90:0:5);

\end{tikzpicture}

\end{document}


How can I do it otherwise?

-

One way to do is to use {$\lbrace$} and the corresponding {$\rbrace$}:

text={{$\lbrace$}hello{$\rbrace$}}


which yields:

Alternatively you could use:

text={{\textbraceleft}hello{\textbraceright}}


Notes:

• Note the additional set of braces.

• The TikZ/PGF manual states for text deocrations:

• Each character in the text is typeset in a separate \hbox...

...