Copier can't access Secure Remote Authentication passphrase option

[grodriguezl]

When a key's passphrase is submitted as a Secure Remote Authentication option, its value is loaded in $RD_PRIVATE_OPTION_NAME which is collected by exec and copy. However this kind of options cannot by used by copiers, so in ssh-copy $RD_PRIVATE_OPTION_NAME is not defined and the script fails.