[tex-live] XeTeX Chinese MWE no longer compiles on pretest

[Scott Kostyshak]

The following minimal example used to compile in TeX Live 2014 as well
as an earlier TeX Live 2015 pretest installation:

\documentclass{article}
\usepackage{xeCJK}

\begin{document}
这个文档是为那些不知道
\end{document}

I now get the following error:

! Undefined control sequence.
<argument> \xe at alloc@intercharclass

Is this expected?

I am on Ubuntu 15.04.
$ xelatex --version
XeTeX 3.14159265-2.6-0.99992 (TeX Live 2015)
kpathsea version 6.2.1
Copyright 2015 SIL International, Jonathan Kew and Khaled Hosny.
There is NO warranty.  Redistribution of this software is
covered by the terms of both the XeTeX copyright and
the Lesser GNU General Public License.
For more information about these matters, see the file
named COPYING and the XeTeX source.
Primary author of XeTeX: Jonathan Kew.
Compiled with ICU version 55.1; using 55.1
Compiled with zlib version 1.2.8; using 1.2.8
Compiled with FreeType2 version 2.5.5; using 2.5.5
Compiled with Graphite2 version 1.2.4; using 1.2.4
Compiled with HarfBuzz version 0.9.40; using 0.9.40
Compiled with libpng version 1.6.17; using 1.6.17
Compiled with poppler version 0.32.0
Compiled with fontconfig version 2.11.93; using 2.11.1
$

Please let me know if my log files would help (from TeX Live 2014 or
TeX Live 2015 early pretest or the most recent TeX Live pretest which
yields this error).

Best,

Scott