There's a race between LinuxPtraceHost's call to Proc.sendRefresh() (to add
assumed un-attached tasks) and LinuxWaitBuilder creating the same task because
it is a fresh attached clone.  The result is a core panic where the clone gets a
stopped event while in the "detached" state.

The fix is to just not do the refresh (but that will take some time as code is
still relying on being able to get a task list when a process isn't under
observation).