No lock warning after it is forced by another user

Apparently when the lock is forced by an user, the first user who took the lock won't get a lock warning if they try to edit the page later.

Reproduction steps:

• Edit Home page with UserA
• Edit Home page in-place with UserB: a lock warning is displayed, force it
• Refresh Home page with UserA, and try editing it again

Expected result:

• the lock warning is displayed again for UserA since UserB is editing it

Obtained result:

• no lock warning anymore for UserA