FTBFS: nplurals = 1 but some messages have 2 plural forms

Created by: jean-christophe-manciot

Ubuntu 19.04 disco solaar 0.9.2-259-gc07c115e (git20190130.c07c115e) python2.7: 2.7.15-8

Building with:

cd packaging
echo ------------------------------
echo Changing DPKG_BUILPACKAGE_OPTS
echo ------------------------------
sed -Ei "s|DPKG_BUILPACKAGE_OPTS=\"-b -us -uc\"|DPKG_BUILPACKAGE_OPTS=\"-i -I --no-sign --build=binary -m'<manciot.jeanchristophe@gmail.com>'\"|g" build_deb.sh

echo ---------------------------------------
echo Forcing debchange to accept our version
echo ---------------------------------------
sed -Ei "s|/usr/bin/debchange|/usr/bin/debchange -b|g" build_deb.sh

echo --------
echo Building
echo --------
./build_deb.sh

leads to:

/usr/lib/python2.7/distutils/dist.py:267: UserWarning: Unknown distribution option: 'install_requires'
  warnings.warn(msg)
/usr/lib/python2.7/distutils/dist.py:267: UserWarning: Unknown distribution option: 'install_requires'
  warnings.warn(msg)
/media/actionmystique/SAMSUNG5-Shared/home/actionmystique/src/Logitech/git-solaar/po/zh_TW.po:7: nplurals = 1...
/media/actionmystique/SAMSUNG5-Shared/home/actionmystique/src/Logitech/git-solaar/po/zh_TW.po:203: ...but some messages have 2 plural forms
/usr/bin/msgfmt: found 1 fatal error