[luatex] 'Out by one' error (?) in \csname messages

[Joseph Wright]

Hello all,

With the TL2014 pretest version of LuaTeX,

    \csname\csname\endcsname

leads to the error

    ! Missing \endcsname inserted.
    <to be read again>
    \^^@csnam\^^@endcsnam
    l.1 \csname\csname\endcsname

which looks like some form of 'out by one' issue.
-- 
Joseph Wright