Comment 22 for bug 1405349

Installed and tested all 3 patched 𝐔𝐧𝐢𝐭𝐲 𝟕 version 7.2.6+14.04.20151021-0ubuntu1 packages on 𝐔𝐛𝐮𝐧𝐭𝐮 𝟏𝟒.𝟎𝟒𝐋𝐓𝐒 "Trusty". I did 3 Test Cases:

[𝐓𝐞𝐬𝐭 𝐂𝐚𝐬𝐞 𝟏]
Ran
sudo true && gdbus call --session --dest org.gnome.ScreenSaver \
     --object-path /com/canonical/Unity/Session --method \
     com.canonical.Unity.Session.ActivateScreenSaver && \
     sleep 1 && sudo chvt 1 && sleep 1 && sudo chvt 7

Result: 𝐒𝐮𝐜𝐜𝐞𝐬𝐬. Doesn't show blank screen forever, shows LockScreen on waiting a few seconds.

[𝐓𝐞𝐬𝐭 𝐂𝐚𝐬𝐞 𝟐]
1. login with your account normally.
2. switch to guest session from the panel menu "Switch Account... -> Guest Session", now it's under guest session and the display is normal.
3. switch back to your user account, then switch to guest session again.

Result: 𝐒𝐮𝐜𝐜𝐞𝐬𝐬. Shows Guest Session without needing to wake up the screen. Shows Login Screen when switching back to main user.

[𝐓𝐞𝐬𝐭 𝐂𝐚𝐬𝐞 𝟑]
Method proposed by @robert-ancell . Triggered LockScreen on Guest Session by typing Super+L inside the guest session.

Result: 𝐒𝐮𝐜𝐜𝐞𝐬𝐬. Well, it's not a blank screen (sleeping screen) anymore but a black screen with mouse pointer visible.

With the new Unity passing all test cases, I think I verified it for inclusion in SRU.