Non database agnostic expression in SQLContentEntityStorage

The SQLContentEntityStorage makes an equal assertment as an expression.

This does not work on all database engines. The database agnostic implementation is to use "CASE WHEN THEN ELSE END" construction.

$query->addExpression('base.' . $this->revisionKey . ' = revision.' . $this->revisionKey, 'isDefaultRevision');

This prevents any revisionable entity from being loaded, resulting in a PDO exception for database engines not supporting inline equal expressions.

Should be replaced with:

$query->addExpression('CASE base.' . $this->revisionKey . ' WHEN revision.' . $this->revisionKey . ' THEN 1 ELSE 0 END', 'isDefaultRevision');