Preserve indentation in multi-line list entry

I would like to put this in a NEWS entry:

The following `threading` methods are now deprecated and should be replaced:

- `threading.activeCount` => :func:`threading.active_count`

- `threading.Condition.notifyAll` =>
    :meth:`threading.Condition.notify_all`

But when blurb generates the NEWS file, it produces:

- bpo-43723: The following `threading` methods are now deprecated and should
  be replaced:

  - `threading.activeCount` => :func:`threading.active_count`

  - `threading.Condition.notifyAll` =>
  :meth:`threading.Condition.notify_all`

Which is invalid rst, because the second line of the list is not indented enough.

It's because blurb uses textwrap.wrap to reflow the text, and that function eats any leading space in the line. Fixing this might require doing something more RST-aware.

まず、blurb における Python's textwrap.wrap の使用箇所を見つけ、ここに示した NEWS エントリで問題を再現します。複数行のリスト項目がどのように再整形されるかを追跡し、生成された出力が有効な reStructuredText に必要なインデントを保持していることを確認します。