static_detach test failing with extra output after reattach

After my re-attach CL for #2157:

This is interesting, with the duplicated "Saw some bb events". I thought I made sure the event callback lists were cleared? Should check that again, but wouldn't more things have broken if they weren't?

This is in release build: maybe the clearing is debug-only?

http://dynamorio.org/CDash/testDetails.php?test=204327&build=18737

pre-DR init in dr_client_main pre-DR start pre-DR detach Saw some bb events re-attach attempt in dr_client_main Saw some bb events Saw some bb events all done