Following up on r1592715, restore support for running tests out of tree on
Windows. This breakage was invisible because the testsuite deadlocked in the
C tests.

* subversion/tests/cmdline/svntest/main.py
  (P): Use current directory, instead of the python directory to restore
    support for out of tree test runs, like on Windows.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1592974 13f79535-47bb-0310-9956-ffa450edef68