Log Message:
py-subprocess32: update to 3.5.4.

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2019-05-20 3.5.4
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 * Promoted 3.5.4rc2 to become 3.5.4.

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2019-05-13 3.5.4rc2
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 * GitHub [#57]: TimeoutExpired and CalledProcessError exceptions can now
   be unpickled.

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2019-05-10 3.5.4rc1
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* GitHub [#61]: Backport the fixes for https://bugs.python.org/issue10963,
  https://bugs.python.org/issue19612, and https://bugs.python.org/issue30418.
  When a child process was so short lived it dies or closes its pipes before
  you call communicate().  When supplying stdin or reading its output in
  this scenario, do not raise an unexpected broken pipe or interrupted
  system call exception.