Perhaps keep this case statement in a separate function as well to keep things clean. Maybe combine with the `fixup_opts` call below. Would need to move the `PutCore` stuff after, but that's no biggie.

Something like:
```erlang
VNodeOpts0 = handle_options(Options, []),
{VNodeOpts, ReturnBody} = maybe_override_returnbody(Postcommit, Options, VNodeOpts0),
PutCore = ...
```