[BUG] org-clock-in opens buffers for all agenda files

[Tom Gillespie]

I just tried to clock in to a task for the first time
in ... a while, and was immediately accosted with
hundreds of buffers being opened.

This seems to be because org-clock-in somehow
calls org-agenda or org-agenda-prepare or something
similar, however I cannot find the call site.

Is there a way to disable this so that clocking does not
destroy my emacs buffer state by starting org-agenda?

Thanks!
Tom