don't prompt with "buffer://"

[jidanni@xxxxxxxxxxx]

When one does M-x w3m, one gets a prompt with
URL (default HOME): buffer://
or
URL (default popup): buffer://

Why not instead make this
URL (default HOME):
or
URL (default popup):

That way one needn't manually delete the "buffer://"
which will always cause an error if one just hits RETURN.