The return value of os.access(FILE, os.X_OK) is not consistent across operating system when executed as "root"

I have tested with Python 2.5 on Linux and Solaris, but there is a bug in python-nose reporting the same behavior with Python 2.6 on Solaris and AIX.
http://code.google.com/p/python-nose/issues/detail?id=423

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On Solaris:

$ ls -al 
-rw-rw-r--   1 buildslave other       1079 May  1 16:25 nose_runner.py

$ ./bin/python 
Python 2.5.6 (r256:88840, Nov  1 2011, 12:19:05) 
[GCC 3.4.3 (csl-sol210-3_4-branch+sol_rpath)] on sunos5
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> os.access('nose_runner.py', os.X_OK)
False

$ sudo ./bin/python 
Python 2.5.6 (r256:88840, Nov  1 2011, 12:19:05) 
[GCC 3.4.3 (csl-sol210-3_4-branch+sol_rpath)] on sunos5
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> os.access('nose_runner.py', os.X_OK)
True

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On Linux:

$ ls -al 
-rw-rw-r-- 1 adi adi  1079 2012-05-02 11:25 nose_runner.py

$ ./bin/python 
Python 2.5.5 (r255:77872, Sep 14 2010, 16:22:46) 
[GCC 4.4.5] on linux2
>>> import os
>>> os.access('nose_runner.py', os.X_OK)
False

$ sudo ./bin/python 
Python 2.5.5 (r255:77872, Sep 14 2010, 16:22:46) 
[GCC 4.4.5] on linux2
>>> import os
>>> os.access('nose_runner.py', os.X_OK)
False