Flutter: erro de instalação

Acabei de clonar o repositório de flutter, atualizar PATH
quando eu corro flutter doctor eu recebo este erro

doutor palpitante

👉 hao@~ $ flutter doctor
Downloading Dart SDK 1.25.0-dev.9.0...
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  1383  100  1383    0     0    385      0  0:00:03  0:00:03 --:--:--   385
[/Users/hao/Documents/flutter/bin/cache/dart-sdk.zip]
  End-of-central-directory signature not found.  Either this file is not
  a zipfile, or it constitutes one disk of a multi-part archive.  In the
  latter case the central directory and zipfile comment will be found on
  the last disk(s) of this archive.
unzip:  cannot find zipfile directory in one of /Users/hao/Documents/flutter/bin/cache/dart-sdk.zip or
        /Users/hao/Documents/flutter/bin/cache/dart-sdk.zip.zip, and cannot find /Users/hao/Documents/flutter/bin/cache/dart-sdk.zip.ZIP, period.

It appears that the downloaded file is corrupt; please try the operation again later.
If this problem persists, please report the problem at
https://github.com/flutter/flutter/issues/new