The availability of the guest is not shown

Creating an event by invitation, entering the invitee's email and clicking the "Show availability" button does not show the actual availability if the email address proposed with the auto-completion is used: username <user@domain.org>

Steps to reproduce:

• create an event from 2pm to 3pm for the user "user1" by selecting the "busy" status
• create an event on the same day on the user's "user2" calendar and invite user1@domain.org by selecting the one proposed with autocompletion: user1 <user1@domain.org>
• click on the show availability button

Expected behaviour:

• is shown as busy in the time period from 14 to 15

Actual behaviour:

• is always shown available

Note: If the invitee is entered with the email address user1@domain.org the problem does not occur.

Thanks to Emiliano Vavassori (Ref: #63805)