#542 another [namespace import] misfeature?

[Don Porter]

came up in the chat:

% namespace eval ns {proc foo {} {}}
% namespace eval ns namespace export foo
% namespace eval ns namespace import ::ns::foo
import pattern "::ns::foo" tries to import from namespace "ns" into itself

Is the error really useful? Or a relic like
the errors thrown by idempotent [namespace import]s
that has already been corrected?