[Bug-wget] No warning printed when using options: -N -O-

[Nik Nyby]

The wget manual states:

  ‘-N’ (for timestamp-checking) is not supported in combination with ‘-O’:
  since file is always newly created, it will always have a very new
  timestamp. A warning will be issued if this combination is used.

(In this section of the manual):
http://www.gnu.org/software/wget/manual/html_node/Download-Options.html#Download-Options

The warning is printed if you do:
  wget -N -O http://example.com

But the warning isn't printed if you do something like:
  wget -N -O- http://example.com


Maybe the statement in the manual should be revised to avoid confusion?

See: https://github.com/docker/docker/pull/12857