mirrorpdf does not work anymore

pstops throws an error:

pstops: page specification error:
  <pagespecs> = [modulo:]<spec>
  <spec>      = [-]pageno[@scale][L|R|U][(xoff,yoff)][,spec|+spec]
                modulo>=1, 0<=pageno<modulo

so the script is useless ; this is quite unfortunate 😞