Ran a test with and without using the patch.

Normal rev266:
----------------
05-22 20:20 INFO   Distro: Found a valid CD for Edubuntu: D:\   <===========THIS IS IGNORED (find_any_cd)
05-22 20:20 INFO   root: Running the installer...
05-22 20:20 DEBUG  WindowsFrontend: __init__...
05-22 20:20 DEBUG  WindowsFrontend: on_init...
05-22 20:20 INFO   WinuiPage: appname=wubi, localedir=C:\DOCUME~1\bcbc\LOCALS~1\Temp\pyl45.tmp\translations, languages=['en_CA', 'en']
05-22 20:20 INFO   WinuiPage: appname=wubi, localedir=C:\DOCUME~1\bcbc\LOCALS~1\Temp\pyl45.tmp\translations, languages=['en_CA', 'en']
05-22 20:21 DEBUG  WinuiInstallationPage: target_drive=C:, installation_size=12000MB, distro_name=Edubuntu, language=en_US, locale=en_US.UTF-8, username=bcbc
05-22 20:21 INFO   root: Received settings
05-22 20:21 DEBUG  CommonBackend: Searching for local CD
05-22 20:21 DEBUG  Distro:   checking whether C:\DOCUME~1\bcbc\LOCALS~1\Temp\pyl45.tmp is a valid Edubuntu CD
05-22 20:21 DEBUG  Distro:     does not contain C:\DOCUME~1\bcbc\LOCALS~1\Temp\pyl45.tmp\casper\filesystem.squashfs
05-22 20:21 DEBUG  Distro:   checking whether D:\ is a valid Edubuntu CD
05-22 20:21 INFO   Distro: Found a valid CD for Edubuntu: D:\  <========THIS IS NOT IGNORED (find_cd)
...
05-22 20:28 DEBUG  TaskList: #### Finished get_metalink
05-22 20:28 DEBUG  TaskList: New task get_file_md5
05-22 20:28 DEBUG  TaskList: #### Running get_file_md5...
05-22 20:30 DEBUG  TaskList: #### Finished get_file_md5
05-22 20:30 ERROR  CommonBackend: Invalid md5 for ISO C:\ubuntu\install\installation.iso (480cee0a7174ea2794c146df8174b14c != 422426bcb782be7f974612b5e85fc289)
None
05-22 20:30 DEBUG  TaskList: ### Finished check_iso
05-22 20:30 ERROR  TaskList: 'NoneType' object has no attribute 'get_info'
Traceback (most recent call last):
  File "\lib\wubi\backends\common\tasklist.py", line 197, in __call__
  File "\lib\wubi\backends\common\backend.py", line 595, in get_iso
  File "\lib\wubi\backends\common\backend.py", line 564, in use_cd
AttributeError: 'NoneType' object has no attribute 'get_info'
05-22 20:30 DEBUG  TaskList: # Cancelling tasklist
05-22 20:30 DEBUG  TaskList: # Finished tasklist
05-22 20:30 ERROR  root: 'NoneType' object has no attribute 'get_info'
Traceback (most recent call last):
  File "\lib\wubi\application.py", line 58, in run
  File "\lib\wubi\application.py", line 132, in select_task
  File "\lib\wubi\application.py", line 158, in run_installer
  File "\lib\wubi\backends\common\tasklist.py", line 197, in __call__
  File "\lib\wubi\backends\common\backend.py", line 595, in get_iso
  File "\lib\wubi\backends\common\backend.py", line 564, in use_cd
AttributeError: 'NoneType' object has no attribute 'get_info'

With the patch:
-----------------
05-22 20:14 INFO   Distro: Found a valid CD for Edubuntu: D:\  <=========THIS IS IGNORED
05-22 20:14 INFO   root: Running the installer...
05-22 20:14 INFO   WinuiPage: appname=wubi, localedir=C:\DOCUME~1\bcbc\LOCALS~1\Temp\pyl39.tmp\translations, languages=['en_CA', 'en']
05-22 20:14 INFO   WinuiPage: appname=wubi, localedir=C:\DOCUME~1\bcbc\LOCALS~1\Temp\pyl39.tmp\translations, languages=['en_CA', 'en']
05-22 20:15 DEBUG  WinuiInstallationPage: target_drive=C:, installation_size=12000MB, distro_name=Edubuntu, language=en_US, locale=en_US.UTF-8, username=bcbc
05-22 20:15 INFO   root: Received settings
05-22 20:15 DEBUG  CommonBackend: Searching for local CD
05-22 20:15 DEBUG  Distro:   checking whether C:\DOCUME~1\bcbc\LOCALS~1\Temp\pyl39.tmp is a valid Edubuntu CD
05-22 20:15 DEBUG  Distro:     does not contain C:\DOCUME~1\bcbc\LOCALS~1\Temp\pyl39.tmp\casper\filesystem.squashfs
05-22 20:15 DEBUG  Distro:   checking whether D:\ is a valid Edubuntu CD
05-22 20:15 INFO   Distro: Found a valid CD for Edubuntu: D:\  <=========THIS IS ALSO IGNORED
...
05-22 20:15 DEBUG  CommonBackend: Could not find any ISO or CD, downloading one now
05-22 20:15 DEBUG  TaskList: New task get_metalink
05-22 20:15 DEBUG  TaskList: ### Running get_metalink...
05-22 20:15 DEBUG  downloader: downloading http://cdimage.ubuntu.com/edubuntu/releases/12.04/release/edubuntu-12.04-dvd-i386.metalink > C:\ubuntu\install
05-22 20:15 DEBUG  downloader: Download start filename=C:\ubuntu\install\edubuntu-12.04-dvd-i386.metalink, url=http://cdimage.ubuntu.com/edubuntu/releases/12.04/release/edubuntu-12.04-dvd-i386.metalink, basename=edubuntu-12.04-dvd-i386.metalink, length=1031, text=None