Comment # 1 on bug 1179766 from Dominique Leuenberger

At least for Firefox, I can see that there are at least two points where
buildroot is being modified during the %build phase - which is no longer
allowed in RPM 4.6 (modifying buildroot is %install phase)

The two points are:

1)
mkdir -p %{buildroot}%{progdir}/browser/extensions

2)
sed -r '/^(ja-JP-mac|ga-IE|en-US|)$/d;s/ .*$//'
$RPM_BUILD_DIR/%{srcname}-%{orig_version}/browser/locales/shipped-locales \
    | xargs -n 1 %{?njobs:-P %njobs} -I {} /bin/sh -c '
        locale=$1
        cp ${MOZCONFIG}_LANG ${MOZCONFIG}_$locale
        sed -i "s|obj_LANG|obj_$locale|" ${MOZCONFIG}_$locale
        export MOZCONFIG=${MOZCONFIG}_$locale
        # nsinstall is needed for langpack-build. It is already built by
`./mach build`, but building it again is very fast
        ./mach build config/nsinstall langpack-$locale
        cp -L
../obj_$locale/dist/linux-*/xpi/firefox-%{orig_version}.$locale.langpack.xpi \
           
%{buildroot}%{progdir}/browser/extensions/langpack-$locale@firefox.mozilla.org.xpi
        # remove prefs, profile defaults, and hyphenation from langpack
        #rm -rf
%{buildroot}%{progdir}/browser/extensions/langpack-$locale@firefox.mozilla.org/defaults
        #rm -rf
%{buildroot}%{progdir}/browser/extensions/langpack-$locale@firefox.mozilla.org/hyphenation
        # check against the fixed common list and sort into the right filelist
        _matched=0
        for _match in ar ca cs da de el en-GB es-AR es-CL es-ES fi fr hu it ja
ko nb-NO nl pl pt-BR pt-PT ru sv-SE zh-CN zh-TW; do
            [ "$_match" = "$locale" ] && _matched=1
        done
        [ $_matched -eq 1 ] && _l10ntarget=common || _l10ntarget=other
        echo
%{progdir}/browser/extensions/langpack-$locale@firefox.mozilla.org.xpi \
            >> %{_tmppath}/translations.$_l10ntarget
' -- {}