bcachefs: Fix btree node merging on write buffer btrees

The btree write buffer flush fastpath that avoids the main transaction
commit path had the unfortunate side effect of not doing btree node
merging.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2023-12-26 22:42:34 -05:00
commit 86dbf8c566