old_contents: import os
  import sys
  import sysconfig
  
  from test import support
  from test import regrtest
  
  # findtestdir() gets the dirname out of __file__, so we have to make it
  # absolute before changing the working directory.
  # For example __file__ may be relative when running trace or profile.
  # See issue #9323.
  __file__ = os.path.abspath(__file__)
  
  # sanity check
  assert __file__ == os.path.abspath(sys.argv[0])
  
  # When tests are run from the Python build directory, it is best practice
  # to keep the test files in a subfolder.  It eases the cleanup of leftover
  # files using command "make distclean".
  if sysconfig.is_python_build():
      TEMPDIR = os.path.join(sysconfig.get_config_var('srcdir'), 'build')
      TEMPDIR = os.path.abspath(TEMPDIR)
      if not os.path.exists(TEMPDIR):
          os.mkdir(TEMPDIR)
      regrtest.TEMPDIR = TEMPDIR
  
  # Define a writable temp dir that will be used as cwd while running
  # the tests. The name of the dir includes the pid to allow parallel
  # testing (see the -j option).
  TESTCWD = 'test_python_{}'.format(os.getpid())
  
  TESTCWD = os.path.join(TEMPDIR, TESTCWD)
  regrtest.TESTCWD = TESTCWD
  
  # Run the tests in a context manager that temporary changes the CWD to a
  # temporary and writable directory. If it's not possible to create or
  # change the CWD, the original CWD will be used. The original CWD is
  # available from support.SAVEDCWD.
  with support.temp_cwd(TESTCWD, quiet=True):
      regrtest.main()
  
new_contents: import os
  import sys
  import sysconfig
  
  from test import support
  from test import regrtest
  
  TEMPDIR = regrtest.TEMPDIR
  
  # findtestdir() gets the dirname out of __file__, so we have to make it
  # absolute before changing the working directory.
  # For example __file__ may be relative when running trace or profile.
  # See issue #9323.
  __file__ = os.path.abspath(__file__)
  
  # sanity check
  assert __file__ == os.path.abspath(sys.argv[0])
  
  # When tests are run from the Python build directory, it is best practice
  # to keep the test files in a subfolder.  It eases the cleanup of leftover
  # files using command "make distclean".
  if sysconfig.is_python_build():
      TEMPDIR = os.path.join(sysconfig.get_config_var('srcdir'), 'build')
      TEMPDIR = os.path.abspath(TEMPDIR)
      if not os.path.exists(TEMPDIR):
          os.mkdir(TEMPDIR)
      regrtest.TEMPDIR = TEMPDIR
  
  # Define a writable temp dir that will be used as cwd while running
  # the tests. The name of the dir includes the pid to allow parallel
  # testing (see the -j option).
  TESTCWD = 'test_python_{}'.format(os.getpid())
  
  TESTCWD = os.path.join(TEMPDIR, TESTCWD)
  regrtest.TESTCWD = TESTCWD
  
  # Run the tests in a context manager that temporary changes the CWD to a
  # temporary and writable directory. If it's not possible to create or
  # change the CWD, the original CWD will be used. The original CWD is
  # available from support.SAVEDCWD.
  with support.temp_cwd(TESTCWD, quiet=True):
      regrtest.main()
  
subject: Fix lib/test/__main__.py to work even outside a Python build.