Add assertion to enforce check of an implicit invariant and add comment about retry of autoinc read semantics. We always reread the table's autoinc counter after attempting to initialize it i.e., we want to guarantee that a read of autoinc valus that is returned to the caller is always covered by the AUTOINC locking mechanism.
Add assertion to enforce check of an implicit invariant and add comment about
retry of autoinc read semantics. We always reread the table's autoinc counter
after attempting to initialize it i.e., we want to guarantee that a read of
autoinc valus that is returned to the caller is always covered by the
AUTOINC locking mechanism.

ollie314/server,ollie314/server,davidl-zend/zenddbi,natsys/mariadb_10.2,natsys/mariadb_10.2,ollie314/server,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,davidl-zend/zenddbi,flynn1973/mariadb-aix,flynn1973/mariadb-aix,davidl-zend/zenddbi,flynn1973/mariadb-aix,ollie314/server,ollie314/server,flynn1973/mariadb-aix,ollie314/server,davidl-zend/zenddbi,flynn1973/mariadb-aix,flynn1973/mariadb-aix,flynn1973/mariadb-aix,davidl-zend/zenddbi,natsys/mariadb_10.2,flynn1973/mariadb-aix,natsys/mariadb_10.2,ollie314/server,natsys/mariadb_10.2,flynn1973/mariadb-aix,davidl-zend/zenddbi,ollie314/server,davidl-zend/zenddbi,natsys/mariadb_10.2,flynn1973/mariadb-aix,ollie314/server,natsys/mariadb_10.2,slanterns/server,ollie314/server,davidl-zend/zenddbi,flynn1973/mariadb-aix,natsys/mariadb_10.2,davidl-zend/zenddbi,davidl-zend/zenddbi,davidl-zend/zenddbi,ollie314/server