Page editing lock not released when the edition is canceled (click on the cancel button)

The editing lock is not released in some case, to reproduce follow these steps :
On a MULTILINGUAL wiki

1. Create a test page Sandbox.testCancelButton

• Set the original language of the page to default ('')
• Translate the page to another language, for example FR

1. Edit the FR translation in wysiwyg
2. Using another user and on another browser try to edit the FR translation of the page created above, normally the page will be locked in edition.
3. Now, go back to the initial browser to the page edited on step 2 and click on the cancel button at the bottom of the page.
4. Go back to the 2nd browser and refresh the locked page and see the results

Expected result: The page is not locked anymore and the user can edit the page
Actual result: The page is still locked