* subversion/tests/cmdline/svndumpfilter_tests.py
  (dropped_but_not_renumbered_empty_revs): Increase explicit pipe buffer
    size to avoid a deadlock that is reproducable on Windows after r1578670.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1578820 13f79535-47bb-0310-9956-ffa450edef68