The ntpath test failure is replicated when the test is ran directly:

~/py/cpython\1$ ./python Lib/test/test_ntpath.py
........................s........E.....
======================================================================
ERROR: test_relpath (__main__.TestNtpath)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "Lib/test/test_ntpath.py", line 314, in test_relpath
    tester('ntpath.relpath("a", "../b")', '..\\'+currentdir+'\\a')
  File "Lib/test/test_ntpath.py", line 16, in tester
    %(str(fn), str(wantResult), str(gotResult)))
test.support.TestFailed: ntpath.relpath("a", "../b") should return: ..\cpython\1\a but returned: ..\1\a

----------------------------------------------------------------------

Here is a patch with a fix of test_ntpath and with simpler fix of test_urllib2.