bcachefs: Fix assertion in bch2_btree_key_cache_drop()

Turns out this assertion was something we could legitimately hit - add a
comment describing what's going on, and handle it.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
This commit is contained in:
Kent Overstreet 2022-08-11 21:06:43 -04:00 • committed by Kent Overstreet
commit 45b033fa1a