In an environment with persistent object caching, concurrent calls
to delete_option() + add_option() can result in the option value
leaking out of the alloptions cache key, and into its own cache
item under the options group, while deleting the value from the
database.
This causes future function calls to add_option() to fail, since
the value already exists in cache (under the wrong key). It also
causes calls to delete_option() to fail, since the value is not
in the database.
This commit forces update_option() instead of the delete + add
combination, as well as removes multiple unnecessary calls to
update the woocommerce_db_version from admin notes and notices.
a100ed67b2