In general, that's not a common practice with bug trackers. Some of the reasons include:
* There are often multiple release branches -- do you close it when it hits the first branch, or close it when it hits all possible branches?
* It makes it much harder to close bugs because it creates a huge lag between when someone works on a bug and when they have to go back, find the bug, and mark it closed.
* The person working on the bug and the person creating a release may be different people.
Changelists for releases are the best place for this sort of information. Also, including the version number at the time of the fix (or intended version number the fix should appear in) can help mitigate the search issue.
- Ken