from koning_robot:

   I noticed that buffer_kill_before_hook gets run when a window is
   closed, but not when an individual buffer is killed.  is this intended?

looks like an error to me

also see issue191

Further thoughts: there is an important distinction between manually
killing a buffer, and having a buffer automatically killed because you
closed its window.  so we will need to think about whether the differences
between those two situations warrant having 2 hooks, or whether we can
just have 1 hook to cover both cases.  If two hooks would be better, was
the existing buffer_kill_before_hook misnamed?

I understand this is an old report, but would it be interesting to patch this? 

Possibly by running buffer_before_kill_hook near the start of kill_buffer.