[luatex] reading font.fonts[] gives an error

[Hironori KITAGAWA]

Hello,

LuaTeX in TeX Live 2013 pretest (x86_64-linux)
with the following source
---
%#!luatex
\input luaotfload.sty
\font\jx=file:KozMinPr6N-Regular.otf:+palt \jx 
\directlua{local t = font.fonts[font.current()]}%
あ
\end
---
gives a strange error:
  > error: ...3/texmf-dist/tex/luatex/luaotfload/luaotfload-merged.lua:7493: 
  > attempt to perform arithmetic on local 'factor' (a nil value)
(The complete log is attached to this mail.)

Of course, this error disappeared if the line 5 is commented out.
I think that the line 5 does nothing harmful...

Regards
Hironori KITAGAWA <h_kitagawa2001 at yahoo.co.jp>
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