Enabling 'Cleanup using Pathauto' under File Path Options also triggers file name cleanup

In a File field definition, when I set the option 'Cleanup using Pathauto' under 'File Paths Options' to TRUE, uploaded files invariably have their file namescleaned in addition to their paths, regardless of the setting for 'Cleanup using Pathauto' under 'File Name Options'. Turning file name cleanup off or on has no impact while file path cleanup is enabled: file names always get cleaned.

Using Drupal 7.21

Steps to reproduce the problem:
1. Create a field of the type File.
2. Set the 'File Paths Options' > 'Cleanup using Pathauto' to TRUE
3. Set the 'File Name Options' > 'Cleanup using Pathauto' to FALSE
4. Create a node and upload a file with spaces in the name
5. Watch the spaces being replaced in the file name after saving the node

EDIT:
The same issue occurs when using the most recent dev version.