bcachefs: Switch a BUG_ON() to a panic()

This assert is popping - rarely - in the CI, this will help us track it
down from the logs.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2023-02-09 15:49:25 -05:00
commit 434b1c75a4