Can't unlock lock screen during Call

Problem

When answering a call from the lock screen, there is no way to swipe up to unlock the screen and then switch to other apps. The normal UI element is no longer there:

Expected Behavior

You should be able to swipe up during a call, unlock with a PIN, and then bring Calls app back to full screen as when screen is unlocked.

Complications

If a user swipes up, they will need some way to get back to the calls app in case they can't unlock or choose not to unlock.

Steps to reproduce

• Get phone to lock screen
• Call phone, answer call
• Attempt to swipe up to unlock phone