qa/589: another aliased error message
qa/589: another aliased error message

This time on Ubuntu 20.04 we're seeing "Unknown server error".

adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp