When upgrading from Drupal 7 using Migrate Drupal UI, paths to the 'Public files directory' and 'Private files directory' can be entered at /upgrade/credentials. The value entered for the private files directory was ignored, causing the public files directory to be used in the migration of private files. This is now fixed. The value entered by the user for the 'Private files directory' is used in the migration.
This only effects upgrade done using the Migrate Drupal UI module.
Before
The value entered in the 'Private files directory' field was ignored.
After
The value entered in the 'Private files directory' field is used for private files.
To reproduce the earlier behavior, enter the same path in both form fields or leave the private files directory blank and the public directory will be used for both.