Go to movie mode, set expo override ON, expose for the dark scene then pan from a dark scene to a bright scene (e.g. the computer montor) and the bug should kick in.
When I set my 1100D in movie mode I can adjust the aperture by pressing the AV button and turn the wheel. I see the screen change in brightness
When I set Expo Override ON, the aperture goes to 5.6 and the screen is very dark.
When I press the AV button and turn the wheel the aperture says at 5.6 and the brightness doesn't change.
I tried several lenses on both sides of the zoom range and every lens I use shows this same effect.
Aparently I do not have the bug. At this time the Expo override ON is useless for me because the aperture stays at 5.6.
I use the latest nightly build (2012Oct21).
Used lenses:
Canon 70-200 F/4 L
Canon 18-135 IS (f/3.5-5.6)
Tokina AT-X 80-400 (f/4.5-5.6)
The 18-55 kitlens is sold so I cannot test that lens.