Using LDAP enrolment with MSAD. Linux Debian Server. Moodle 2.9.1.
When I run sync.php, as soon as it gets to a course that has students to unenrol, the script halts and produces the following error.

Potential coding error - active database transaction detected during request shutdown.
line 529 of /enrol/ldap/lib.php: call to moodle_database-start delegated transaction
line 61 of /enrol/ldap/cli/sync.php: call to enrol_ldap_plugin sync_enrolments