Installing Python 3.3 on Arch tonight, two tests failed:

[157/372] test_import
test test_import failed -- Traceback (most recent call last):
  File "/tmp/packerbuild-1000/python33/python33/src/Python-3.3.6/Lib/test/test_import.py", line 307, in test_timestamp_overflow
      os.stat(compiled)
      FileNotFoundError: [Errno 2] No such file or directory: '__pycache__/@test_9865_tmp.cpython-33.pyc'

Another test:

[251/372/1] test_pyexpat
test test_pyexpat failed -- Traceback (most recent call last):
  File "/tmp/packerbuild-1000/python33/python33/src/Python-3.3.6/Lib/test/test_pyexpat.py", line 607, in test2
      parser.Parse(xml, True)
      xml.parsers.expat.ExpatError: XML declaration not well-formed: line 1, column 13

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/tmp/packerbuild-1000/python33/python33/src/Python-3.3.6/Lib/test/test_pyexpat.py", line 610, in test2
      self.assertEqual(str(e), 'XML declaration not well-formed: line 1, column 14')
      AssertionError: 'XML declaration not well-formed: line 1, column 13' != 'XML declaration not well-formed: line 1, column 14'
      - XML declaration not well-formed: line 1, column 13
      ?                                                  ^
      + XML declaration not well-formed: line 1, column 14
      ?

Test results:

347 tests OK.
2 tests failed: test_import test_pyexpat
23 tests skipped:
    test_codecmaps_cn test_codecmaps_hk test_codecmaps_jp
    test_codecmaps_kr test_codecmaps_tw test_curses test_devpoll
    test_gdb test_kqueue test_msilib test_ossaudiodev test_smtpnet
    test_socketserver test_startfile test_timeout test_tk
    test_ttk_guionly test_urllib2net test_urllibnet test_winreg
    test_winsound test_xmlrpc_net test_zipfile64
Those skips are all expected on linux.
==> ERROR: A failure occurred in check().
Aborting...
The build failed.

Easiest fix was to skip the tests:

# packer -S packer33

When packer asked to edit the PKGBUILD I said yes, and removed the check() function in which the tests were running.