[tex-live] TikZ bug in TeXLive 2007

[John Murdie]

Someone here has encountered the problem of writing a medium space in
math mode (\:) when TikZ is used (also reported here:
http://osdir.com/ml/tex.pgf.user/2006-12/msg00029.html ), try:

$ cat > bug.tex
\documentclass{article}
\usepackage{tikz}
\begin{document}
  $a {\:} b$
\end{document}
$ pdflatex bug
This is pdfTeXk, Version 3.141592-1.40.3 (Web2C 7.5.6)
 %&-line parsing enabled.
entering extended mode
(./bug.tex
LaTeX2e <2005/12/01>
Babel <v3.8h> and hyphenation patterns for english, usenglishmax, dumylang, noh
yphenation, arabic, basque, bulgarian, coptic, welsh, czech, slovak, german, ng
erman, danish, esperanto, spanish, catalan, galician, estonian, farsi, finnish,
 french, greek, monogreek, ancientgreek, croatian, hungarian, interlingua, ibyc
us, indonesian, icelandic, italian, latin, mongolian, dutch, norsk, polish, por
tuguese, pinyin, romanian, russian, slovenian, uppersorbian, serbian, swedish, 
turkish, ukenglish, ukrainian, loaded.
(/usr/local/pkg/texlive-2007/texmf-dist/tex/latex/base/article.cls
Document Class: article 2005/09/16 v1.4f Standard LaTeX document class
...
No file bug.aux.
(/usr/local/pkg/texlive-2007/texmf-dist/tex/context/base/supp-pdf.tex
[Loading MPS to PDF converter (version 2006.09.02).]
)
! Use of \pgfutil at xifnch doesn't match its definition.
l.4   $a {\:}
              b$  % other error results from omitting accolades
? X
$

The same problem doesn't happen with MikTeX version 2.6.2627 on a
Windows system here; I presume a solution to this problem has been
solved in a later version of TikZ provided there.

Suggested solution? The problem doesn't happen with the thick space (\;)
or the thin space (\,), but it would be peverse to change to using one
of the first or, say, two of the last. :-)

I will try installing the newer TikZ under texmf-local, but I fear that
this might possibly break something else.

John A. Murdie
Department of Computer Science
University of York
UK