Python 2.7.7 seems to contain a regression of issue #10162 as compared with 2.7.6, re-introduced by the fix of issue #9291.

import mimetypes
mimetypes.init()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Program Files\INRO\Emme\Emme 4\Emme-4.1.3\Python27\lib\mimetypes.py",
 line 348, in init
    db.read_windows_registry()
  File "C:\Program Files\INRO\Emme\Emme 4\Emme-4.1.3\Python27\lib\mimetypes.py",
 line 256, in read_windows_registry
    with _winreg.OpenKey(hkcr, subkeyname) as subkey:
WindowsError: [Error 5] Access is denied

Whereas with Python 2.7.6 on the same system, this doesn't generate any errors.

It looks like in Python 2.7.6, "with _winreg.OpenKey(hkcr, subkeyname) as subkey:" was within a try-except which was moved with the patch for issue#9291 in Python 2.7.7

I have attached patch to #21652 which partly reverts patch applied in #9291. I think we'll have to add one more test for this case.

Test added.

New changeset ee33d61f5e4b by Benjamin Peterson in branch '2.7':
add a test for access errors from OpenKey (closes #21871)
http://hg.python.org/cpython/rev/ee33d61f5e4b