Fixup skype/update.sh to be more defensive
Fixup skype/update.sh to be more defensive

jakirkham/dockerfiles,atyenoria/dockerfiles,atyenoria/dockerfiles,adammcarth/dockerfiles,jakirkham/dockerfiles,rot26/dockerfiles,atyenoria/dockerfiles,rot26/dockerfiles,pmav99/dockerfiles,jakirkham/dockerfiles,adammcarth/dockerfiles,atyenoria/dockerfiles,pmav99/dockerfiles,rot26/dockerfiles,adammcarth/dockerfiles,jakirkham/dockerfiles,pmav99/dockerfiles,pmav99/dockerfiles,rot26/dockerfiles,jakirkham/dockerfiles,adammcarth/dockerfiles