Doing a is_a($lbfactory, \LBFactory) no longer works in 1.29+. It seems \Wikimedia\Rdbms\LBFactory does not define a class_alias and while the use of namespaced classes is appreciated, please wait at least until the next LTS release before removing interfaces and classes otherwise you are inviting unnecessary failures for extensions that need to support 1.27+.
Related Gerrit Patches:
|mediawiki/core : REL1_29||rdbms: Add compat alias for renamed LBFactory class|
|mediawiki/core : master||rdbms: Add compat alias for renamed LBFactory class|