I think the following may be a typo:
* Caller is responsible for ensuring that no other backend can access the
* storage underlying this tuple, either by holding an exclusive lock on the
- * buffer containing it (which is what lazy VACUUM does), or by having it by
+ * buffer containing it (which is what lazy VACUUM does), or by having it be
* in private storage (which is what CLUSTER and friends do).
If so, attached is the patch.
Thanks,
Amit