7.2.1

Bug fixes

• Fixed a regression in 7.2.0 where a subclass of
  MultiDictProxy or CIMultiDictProxy
  that converted its argument in its own __init__() raised
  TypeError before that __init__() ran; such a subclass got an
  empty multidict until its __init__() set the proxied one
  -- by @asvetlov.

  Related issues and pull requests on GitHub:
  #1824, #1825.

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