There are multiple places in the code base where the database object is not cached as a variable for re-use. As a result, the code is not DRY and developers may be initially confused by inconsistency when they expect to see $db->quoteName() but $query->quoteName() is written. There are some occurrences where $this->getDbo() is called multiple times within the same method which is not ideal / best practice (I found one occurrence within a loop).

The advised fix does not need to change any behavior and as far as I can tell there is no bug in the current implementation.

To find the occurrences just search on "$this->getDbo()" in your IDE and observe the number of times the getDbo() method is called. If more than one, then declare a variable on the first call and re-use the variable on all subsequent occurrences. If the getDbo() method is called over and over within a loop, declare $db prior to entering the loop and only use $db within the loop.