That's a bad idea IMO. Version field as "version where the bug was found" provides useful information as an "upper bound", i.e. for v_N, the bug appeared in V_i...V_N-1, V_N If you change the meaning of the field, you'd have to examine the bug history to find that info.
When would that information be useful apart from regressions? If it's only useful for regressions, aren't we optimizing for an uncommon case?
Generally, regressions will have that information in a comment anyway, and indirectly in the Regression SHA1 field.