[Bug-AUCTeX] Preview fails for all when using pgf 3.0.0

[Hans van den Bogert]

Copied from ‘downstream’ macports bug at https://trac.macports.org/ticket/43189:

Reproduction succeeded on:
* Mac OSX, using emacs-app 24.3, pgf 3.0.0 from macports
* Ubuntu 13.10 using emacs 24.3 (official ubuntu repo), pgf 3.0.0 from tar ball

Steps to reproduce 
1) Take a tex file which uses package tikz 
2) load it into emacs.app which has auctex and latex-preview enabled. 
3) preview the document: C-c C-p C-d

expected: previews for the sections and other environments

got: no previews, instead we got "stop-signs"

example tex:

— begin-latex-code-snippet --

\documentclass{report}
\usepackage[british]{babel}
\usepackage{tikz}
\begin{document}

\begin{titlepage}
foo
\end{titlepage}
\chapter{}

\end{document}

— end-latex-code-snippet --