Revert "[3.8] bpo-27657: Fix urlparse() with numeric paths (GH-16839)" (GH-18525)

Revert "[3.8] bpo-27657: Fix urlparse() with numeric paths (GH-16839)" (GH-18525)

This reverts commit 0f3187c1ce3b3ace60f6c1691dfa3d4e744f0384.

The change broke the backwards compatibility of parsing behavior in a
patch release of Python (3.8.1). A decision was taken to revert this
patch in 3.8.2.

In https://bugs.python.org/issue27657 it was decided that the previous
behavior like

>>> urlparse('localhost:8080')
ParseResult(scheme='', netloc='', path='localhost:8080', params='', query='', fragment='')

>>> urlparse('undefined:8080')
ParseResult(scheme='', netloc='', path='undefined:8080', params='', query='', fragment='')

needs to be preserved in patch releases as number of users rely upon it.

Explicitly mention the releases involved with the revert in NEWS.
Adopt the wording suggested by @ned-deily.