Browser Behavior Change
Daniel, sorry for the delayed response.
I upgraded an installation to 3.50. This isn't one of the accounts I was experiencing the issue with, but so far I'm unable to reproduce the auto-fill situation.
If this should happen in the future with 3.50, I'll post back.
I haven't tried the Daniel's fix with 3.50 - used the original files. With 3.50 I haven't experienced the random password auto-fill in the search box, so I've not yet need the fix.
I say, give it a try!