The node pointer was not moving properly along the jwt_cert_tree during
the deinit which ended in a double free during cleanup (or when checking
a configuration that used the jwt_verify converter with an explicit
certificate specified).
This patch fixes GitHub issue #1533.
It should be backported to 2.5.
node = ebmb_first(&jwt_cert_tree);
while (node) {
entry = ebmb_entry(node, struct jwt_cert_tree_entry, node);
+ ebmb_delete(node);
ha_free(&entry);
node = ebmb_first(&jwt_cert_tree);
}