[O] math in footnotes not exported correctly when a buffer is narrowed

[Mark Edgington]

I've noticed a bug in org-mode's LaTeX exporting of footnotes when a
buffer is narrowed to a particular section.  To reproduce, try to
export the following org-file to a LaTeX document, and inspect the
resulting LaTeX code -- it will have stripped the math environment off
of "\tau_s":


* Test Section
Here we test whether the footnote is exported correctly [1].  Be sure to narrow
the buffer to this section only before doing a LaTeX export.
* Footnotes
[1] $\tau_s$ is blah blah blah.


Let me know if there's a workaround for this (apart from just "don't
narrow the buffer").  Thanks!

Regards,

Mark