We are de-emphasising attaching (see [22630]) but this is existing
core functionality and will remain for now. This commit just cleans
it up a bit so as to be less embarrassing.
props lessbloat, helenyhou.
fixes#20164.
git-svn-id: https://develop.svn.wordpress.org/trunk@22723 602fd350-edb4-49c9-b593-d223f7449a82