Stitching: failed test: ParallelFeaturesFinder.IsSameWithSerial (master branch)

[alalek]

Nightly build (sporadic failures on Windows):

[ RUN      ] ParallelFeaturesFinder.IsSameWithSerial
C:\build\master-win64-vc14\opencv\modules\stitching\test\test_matchers.cpp(103): error: Expected equality of these values:
  countNonZero(diff_descriptors)
    Which is: 12691
  0
C:\build\master-win64-vc14\opencv\modules\stitching\test\test_matchers.cpp(103): error: Expected equality of these values:
  countNonZero(diff_descriptors)
    Which is: 12691
  0
...

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Problem is related to ORB descriptors (not bit-exact between runs for some reasons)