This question already has an answer here:
Take this recent (and highly irritating) bug for example. Our one and only Oded fixed it quickly but for the fix to actually have any effect, code must be "deployed" first, action that might take even days, especially now with SQL playing tricks on the team.
Until the fix is deployed, the bug still exists.
- Mark status-completed since as far as the dev is concerned, it's fixed and it's just matter or time until all we enjoy it. That's by far the norm here in Meta.
- Bug exists so don't put any tag and wait until the fix is actually out there (maybe even wait for OP to confirm) before tagging as completed. Concern here is forgetting to tag leaving bug reports open even though they're actually fixed.
Personally I prefer #2 though it's really not that crucial. Can anyone see more aspects or reasoning in addition to what I brought here?