I figured that v1.61 had the initial line in it; 1.63 added the comment explaining its purpose. (the diffs are ugly, though, and hard to tell what lines went where sometimes)

The fix was in 1.75, though, over a year later. In the middle is v1.69, tagged as the release version for OpenBSD 3.0 (and the branch point for 3.1)

1.75 looks like the release version for 3.1 (and branch point for 3.2), so the bug would have been present in the released 3.0 version.