Fix tkinter regression introduced by the security fix in #16248.
Add NEWS entry for c18c18774e24.
Add a NEWS entry for b9b521efeba3.
merge with 3.2
#18206: Fix test for existence of license URL.

It now always checks, instead of only when the LICENSE file doesn't exist.  It
is also protected by the 'network' resource, and uses a HEAD request since we
are only doing an existence check.