add safeguard for attempts to install package.xml 1.0-based packages
add safeguard for attempts to install package.xml 1.0-based packages

git-svn-id: 71b65f7ff3646a85e1ba76c778efde6466075005@285258 c90b9560-bf6c-de11-be94-00142212c4b1

pyrus/Pyrus,pyrus/Pyrus