# Pgfplots fails to generate boxplots for some data set

I use pgfplots to generate boxplots, however with some small data sets as the following, I get an error message.

 speed
2
3
1
2
2
11


Here is the error message :

Sorry, an internal routine of the floating point unit got an ill-floating point number '. The unreadable part was near ''


To avoid this problem, I need to add white noise to my data set when generating it, but it is only a dirty workaroud. Do you know how to avoid the pgfplots error message ?

You can for example try the following code :

\documentclass{article}
\usepackage{pgfplots,filecontents}
\pgfplotsset{compat=1.9}
\usepgfplotslibrary{statistics}

\begin{filecontents}{test.dat}
speed
2
3
1
2
2
11
\end{filecontents}

\begin{document}
\begin{tikzpicture}
\begin{axis}
`