The attached file can be dropped into a detectors directory
and the server restarted.

To test with it, start multiple updates via email, web and
email/pgp and the detector will put out data like:

Example output when the web interface changes item 3 and the email
(non pgp) interface changes item 4:

txSourceCheckAudit(3) pre db.txSource: cgi
txSourceCheckAudit(4) pre db.txSource: email
txSourceCheckAudit(3) post db.txSource: cgi
txSourceCheckAudit(4) post db.txSource: email
txSourceCheckReact(4) pre db.txSource: email
txSourceCheckReact(4) post db.txSource: email
txSourceCheckReact(3) pre db.txSource: cgi
txSourceCheckReact(3) post db.txSource: cgi

Note that the calls are interleaved, but the proper
txSource is associated with the same ticket.