tests/test-dirstate-race.t

tests: remove special handling for undefined memoryview

'memoryview' was introduced in Python 2.7. 4adc090fa2fb added code
to filterpyflakes.py to ignore "undefined name 'memoryview'" pyflakes
warnings. Since we no longer support <Python 2.7, we can remove this
workaround.

  $ hg init
  $ echo a > a
  $ hg add a
  $ hg commit -m test

Do we ever miss a sub-second change?:

  $ for i in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20; do
  >     hg co -qC 0
  >     echo b > a
  >     hg st
  > done
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a