Eu baixei o arquivo .xip beta do Xcode 8. Não consigo descompactar. Abrir o arquivo fica parado por horas dizendo "Verificando ..."

Se eu tentar na linha de comando, obtenho o seguinte ...

Downloads unzip Xcode_8_beta.xip 
Archive:  Xcode_8_beta.xip
  End-of-central-directory signature not found.  Either this file 
  is not a zipfile, or it constitutes one disk of a multi-part archive.        

  In the latter case the central directory and zipfile comment will be
  found on the last disk(s) of this archive. unzip:  cannot find 
  zipfile directory in one of Xcode_8_beta.xip or Xcode_8_beta.xip.zip, 
  and cannot find Xcode_8_beta.xip.ZIP, period.