Comment # 10 on bug 1039951 from Dr. Werner Fink

(In reply to Leon Meier from comment #9)
> > Beside this: What does "May work with versions 2.6 and 2.6a." mean? Works or does not work?
> 
> Debian testing has fontspec 2.6; both bugs are out.
> Cygwin has fontspec 2.6a; the italics bug is out, and I know nothing about
> the  \texttt bug in cygwin.
> 
> I have not tested newer fontspec in OpenSuse, since this would require
> installation into a local (?) texmf tree rather than simply copying a .sty
> file. My chance of messing up with local (?) texmf installations is
> relatively high as of now.
> 
> To compile, you need to have texlive-cm-unicode installed, which contain
> computer modern unicode fonts.
> 
> For the (weakly related ?) \texttt bug, I'll file another report as you said.

Maybe an update would help, nevertheless for this  I've to try
 ftp://ftp.tug.org/texlive/tlpretest/archive/fontspec.tar.xz
 ftp://ftp.tug.org/texlive/tlpretest/archive/fontspec.doc.tar.xz
and hope that no other stuff breaks with this.  To make this work I've first to
update the texlive.tlpdb.xz to reflect the change in the file lists. Then
runnin g the perl script out from the Meta package to (re)autogenerate all spec
files ... after this all has to be tested out.

Args ... at least /usr/share/texmf/tex/xelatex/xecjk/xunicode-addon.sty aka
package texlive-xecjk is referencing
(/usr/share/texmf//tex/latex/fontspec/)tuenc.def :

\@ifpackageloaded { xunicode } { }
  {
    \clist_get:NNF \g__xunadd_encname_clist \UTFencname
      {
        \file_if_exist:nTF { tuenc.def }
          { \tl_set:Nn \UTFencname { TU } }
          {
            \sys_if_engine_xetex:TF
              { \tl_set:Nn \UTFencname { EU1 } }
              { \tl_set:Nn \UTFencname { EU2 } }
          }
        \clist_gset_eq:NN \g__xunadd_encname_clist \UTFencname
      }
    \sys_if_engine_xetex:TF
      { \RequirePackage { xunicode } }
      {
        \cs_set_eq:NN \__xunadd_tmp:w \XeTeXpicfile
        \cs_set_eq:NN \XeTeXpicfile \prg_do_nothing:
        \RequirePackage { xunicode }
        \cs_set_eq:NN \XeTeXpicfile \__xunadd_tmp:w
      }
  }

the other font def/fd files of texlive-fontspec 2.5a might also be referenced
by contructing the files names later on ... this opens a can of worms, and this
is exactly not what I want