PHPLIB-510: Don't check exception message for empty strings
PHPLIB-510: Don't check exception message for empty strings

mongodb/mongo-php-library,jmikola/mongo-php-library,mongodb/mongo-php-library,mongodb/mongo-php-library,jmikola/mongo-php-library,jmikola/mongo-php-library,10gen-labs/mongo-php-library-prototype,jmikola/mongo-php-library,mongodb/mongo-php-library,jmikola/mongo-php-library-prototype