I don't know who uses the load_mime_types method; but it is
conceivable that a user would want to read the results of a
command instead of reading a regular file to load MIME types.

None of the WEBrick-related code in Ruby or default/bundled gems
seems to rely on this method; but it is likely 3rd-party code does.

* lib/webrick/httputils.rb (load_mime_types): note Kernel#open behavior
  [Misc #14216]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61402 b2dd03c8-39d4-4d8f-98ff-823fe69b080e