Fixed in? Note the build number for a fixed case
If a user creates a new case, he can fill in the field "Fix for" to give a date/version where the case has to be fixed. I think, this is a kind of "wish" of the user.
The release in which the fix actually took place is information that is of more importance than the, as you mention, "wish" fix, so use the Fix For to correspond to the actual fix release. I.e., change it if needed.
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