One seems as good a choice as zero if a non-null value is to be returned.
"Also, last_value will reflect the latest value reserved by any session, whether or not it has yet been returned by nextval."
I don't understand how last_value can return anything if nextval hasn't been called at least one. So if there is a bug here it's that the value one is returned instead of null.
Zero is a valid value for the sequence, just change the start value for a newly created sequence to zero.
Reasoning: In every case except the uninitialised case, last_value is the same as the current value of the sequence,
which is the same as the number of rows in the table (assuming no deletions).
This point doesn't seem relevant. That isn't what the value represents so basing the premise of a bug report on it is wrong.
