I have decided...

[acroyear]

That the opposite of a Schoedinbug needs a name.

Unusual software bug - Wikipedia, the free encyclopedia:

A schroedinbug is a bug that manifests only after someone reading source code or using the program in an unusual way notices that it never should have worked in the first place, at which point the program promptly stops working for everybody until fixed.

My testers run into the opposite (but it's not quite a Heisenbug) - they hit a problem that repeats itself until I stare at the code and follow every function/method call and determine that there simply is no way that bug could possibly happen...

...and the next run it disappears permanently, without a single change in code or environment.

Comments

[tchwrtr.livejournal.com]

It's the "over the shoulder" fix. Someone else watching as you attempt to show it to them makes the bug go away.

[javasaurus.livejournal.com]

is this like being able to run off the edge of a cliff and ignore gravity until you look down?

[acroyear70.livejournal.com]

That's the Schroedinbug.

The anti form is more like the painting of a tunnel on a wall remaining a rock-solid painting until the roadrunner runs through it, from which point it remains a perfectly working tunnel with a truck coming to hit you.

The Heisenbug Solution

[ren-tigger.livejournal.com]

When I run into the Heisenbug, I have come to accept it is a reflexive fix. You are looking at the code, and reflexively fix that misplaced comma as you scan everything. The action is not remembered as it was so small. And ya know what they say about the small things.
I have caught myself on this at least twice (TTP for creating working copies) and for the life of me I could not remember making any changes to comma's, but I was the only one touching the code.
So again, the annoying (but useful) reflex fix saves the day.

[sequentialscott.livejournal.com]

It's just sufficiently advanced technology.

[faireraven.livejournal.com]

Magic, eh?