image field in user_profile_form results in "An AJAX HTTP request terminated abnormally"

When user_profile_form is embedded in a custom page, use of the image field results in ajax errors, even if user.pages.inc is included in the custom page.

Steps to reproduce:

1. Fresh install of drupal 7.12.
2. Install the attached module, filetest. This module creates a very simple page with an embedded user_profile_form.
3. Go to the modules admin page and enable the filetest module.
4. Go to admin/config/people/accounts/fields -- create a new image field.
5. Go to ?q=myadmin/1 and attempt to upload an image using the field you added in step #3. You will see an error alert like the one posted below.

An AJAX HTTP request terminated abnormally.
Debugging information follows.
Path: /drupal7fresh/?q=file/ajax/field_image/und/0/form-5NgLMXllXPAD70TLL5In5XB49hPZI9jwBUdMsKozaB4
StatusText: n/a
ResponseText: user_profile_form
ReadyState: undefined