The version affected are:
v6.14/00, v6.14/02, v6.14/04, v6.14/06, v6.14/08,
v6.16/00
The tip of the patch branch v6.14 and v6.16 and the version v6.18/00 and later are not affected
The problem is due to commit 8c9c1a3fbe3a1c5704635f8941abeb9596104c77 (Change to onfile format without a class version upgrade).
And yes this means we need to tag v6.14 and v6.16 very soon.