pgfplots：放大 x 限制绝对值和日期坐标

Question

将日期坐标的 x 范围扩大到绝对值，这曾经用于 pgfplots 1.4，但使用较新的版本 1.8 时会出现错误。有人能为下面的最小示例提出可行的解决方案吗？

\documentclass{article}
\usepackage{pgfplots}
\usepgfplotslibrary{dateplot}
\begin{document}
\begin{tikzpicture}
\begin{axis}[
date coordinates in=x,
xtick=data,
xticklabel style=
{rotate=90,anchor=near xticklabel},
xticklabel=\day. \hour:\minute,
date ZERO=2009-08-18,% <- improves precision!
enlarge x limits={abs=2009-08-18 06:00},
]
\addplot coordinates {
(2009-08-18 09:00, 050)
(2009-08-18 12:00, 100)
(2009-08-18 15:00, 100)
(2009-08-18 18:35, 100)
(2009-08-18 21:30, 040)
(2009-08-19,       020)
(2009-08-19 3:00,  000)
(2009-08-19 6:0,   035)
};
\end{axis}
\end{tikzpicture}
\end{document}