Bug? git config and --unset are not inverses

It looks like git config --unset may leave an orphaned section, but a subsequent set adds a new section:

$ git config --file=myconfig section.foo true
$ git config --file=myconfig --unset section.foo
$ cat myconfig
[section]
$ git config --file=myconfig section.foo true
$ cat myconfig
[section]
[section]
       foo = true
$ git --version
git version 2.5.0.rc2.392.g76e840b

Dave Borowitz <dborowitz@google.com> writes:

Old news known for at least several years.  Patches welcome ;-)

The most recent round of the discussion is here:

  http://thread.gmane.org/gmane.comp.version-control.git/219505/focus=219524