bug#44770: chown: warn about the dot when encountering it

[積丹尼 Dan Jacobson]

Maybe print warning messages when encountering the dot,
(info "(coreutils) chown invocation")
Else Grandpa won't ever know,
https://github.com/scop/bash-completion/issues/468
until one day when it's too late...
(And his program starts messing things up on some other system.)