We had our big launch, and of course a few days before had staff madly adding Face to Face sessions (a few hundred)
We were going through the logs and kept finding these seamlessly random students have added a F2F session - needless to say we were incredibly confused.
After some chasing, we have found that F2F was injecting into the mdl_log database, and for some reason using the activityid as the userid - hence why we were getting random students in the log... (Including students that had never logged in)
I found that line 209 in sessions.php seems to be the culprit
add_to_log($course->id, 'facetoface', 'added session', 'facetoface', 'sessions.php?f='.$facetoface->id, $facetoface->id, $cm->id);
My suggested correction is
add_to_log($course->id, 'facetoface', 'added session', 'sessions.php?f='.$facetoface->id, $facetoface->id, $cm->id);
Let me know if you want me to raise a tracker for this? (I haven't done one before.... could be interesting)