[O] Bug: Regression in ox-texinfo export

[Oleh Krehel]

At the current git master, the org source:

    #+BEGIN_TEXINFO
    @quotation
    Permission is granted to copy, distribute and/or modify this document
    under the terms of the GNU Free Documentation License, Version 1.3 or
    any later version published by the Free Software Foundation; with no
    Invariant Sections, with the Front-Cover Texts being ``A GNU Manual,''
    and with the Back-Cover Texts as in (a) below.  A copy of the license
    is included in the section entitled ``GNU Free Documentation License.''
    
    (a) The FSF's Back-Cover Text is: ``You have the freedom to copy and
    modify this GNU manual.''
    @end quotation
    #+END_TEXINFO

results in the following .texi output:

    @TEXINFO
    @@quotation
    Permission is granted to copy, distribute and/or modify this document
    under the terms of the GNU Free Documentation License, Version 1.3 or
    any later version published by the Free Software Foundation; with no
    Invariant Sections, with the Front-Cover Texts being ``A GNU Manual,''
    and with the Back-Cover Texts as in (a) below.  A copy of the license
    is included in the section entitled ``GNU Free Documentation License.''
    
    (a) The FSF's Back-Cover Text is: ``You have the freedom to copy and
    modify this GNU manual.''
    @@end quotation
    @end TEXINFO

This was done with `emacs -Q', no extra code except (require 'ox-texinfo).

Note that the above org source works fine with the built-in Org-mode:

    @quotation
    Permission is granted to copy, distribute and/or modify this document
    under the terms of the GNU Free Documentation License, Version 1.3 or
    any later version published by the Free Software Foundation; with no
    Invariant Sections, with the Front-Cover Texts being ``A GNU Manual,''
    and with the Back-Cover Texts as in (a) below.  A copy of the license
    is included in the section entitled ``GNU Free Documentation License.''
    
    (a) The FSF's Back-Cover Text is: ``You have the freedom to copy and
    modify this GNU manual.''
    @end quotation
    
    @c Emacs 25.0.50.4 (Org mode 8.2.10)

regards,
Oleh