[Content editor]Cancel does not work for document editing

Description

After the Keep draft changes, the Cancel button in the Document editor in the Content perspective is not working anymore.

Steps to reproduce:

1. Go to the Content perspective

2. Select a document

3. Edit the document

4. Change the title of the document

5. Click Cancel

6. Click OK to discard the changes

Expected result:

The changes in step 4 are discarded.

Actual result:

The changes in step 4 are saved.