Actually, I disagree with the last contention, MrPhil.
Bugs in previous versions which are known and acknowledged (or more importantly, fixed) in new releases can require people to upgrade. Sorry... but if someone refuses to upgrade when there is a fixed version out there, then what happens is on their own head. If someone doesn't keep track of the things fixed in upgrades, then THEY are acting stupidly.
So, fixing it (my preference) to some reasonable standard or removing it (I hope not) in 2.1 is acceptable.
1.0 is at end of life... ignore it.
1.1 has been stated, numerous times, to be in security release mode only... If people really want to make a stink about it, then kill the function in 1.1 with the next security release, but I see no point in wasting time on a version which is outdated and replaced.
(honestly, if it were up to me, I would encourage the immediate sunset of 1.0 and the planned sunset of 1.1 by next year (instead of hanging on to outdated versions like we seem to do) -- but that's neither here not there, for this issue.)
and as for your statement "would have been revealed with more than cursory testing", I disagree.... I don't think I have actually had it fail on me, across 8 sites on 5 different hosts, machines, etc. I'll admit, it does seem to be an issue with some folks. Not sure what the common factor is which causes it to fail for them, but I'd hardly say that it was so obviously broken that it should have been immediately obvious (considering the length of our beta process, really?)