Description of problem:
I install frescobaldi, but there is no translation available.

But I look in the rpm source and I can see that the .mo file is present in frescobaldi_app/po.

For test I rebuild with rpmbuild, but there are no .mo files in usr/lib/python2.7/site-packages/frescobaldi_app/po.

I look the spec and I see that : 
.....................................
## File lists
# Create the lang file. %%find_lang does not handle .po files
for file in %{buildroot}%{python_sitelib}/%{name}_app/po/*.mo; do
    bn=$(basename $file)
    language=$(basename $file|cut -f 2 -d _|sed 's|\..*||')
    echo %%lang\($language\) %{python_sitelib}/%{name}_app/po/$bn >> frescobaldi.lang
    done

...................
%files -f %{name}.lang
%doc ChangeLog COPYING README* THANKS TODO
%{_bindir}/%{name}
%{python_sitelib}/%{name}_app
# the following is in our lang file
%exclude %{python_sitelib}/%{name}_app/po/*.mo
%{python_sitelib}/%{name}-%{version}-py2.7.egg-info
%{_datadir}/applications/%{name}.desktop
%{_datadir}/icons/hicolor/scalable/apps/%{name}.svg
%{_mandir}/man1/*

For test I modify the line : 

%exclude %{python_sitelib}/%{name}_app/po/*.mo

by: 
%{python_sitelib}/%{name}_app/po/*.mo

I rebuild with this new spec, compilation work with warning (package .mo listed twice)

I install this new rpm and I have the translation.

Can you rebuild a package with a new spec and with translation ?