Discovered in MDL-65252. The test_update_discussions_post_post method had to be changed as part of migrating it over to use get_discussion_posts (was previously using get_forum_discussion_posts web service method), because the new method does not provide any information on inline attachments. We should fix this and update the test with the old assertions.

https://github.com/lameze/moodle/compare/c307f3b138...MDL-65252-master#diff-10af010d7e6592112804e8f20d0a5831a5f9cb8dd204ab6c05eb82634ef11270L3335