`dolt_merge` stomps working set

[tbantle22]

When you merge to a branch with a working set the merge is successful and the working changes are gone

doltgres=> select * from dolt_status;
    table_name    | staged |  status
------------------+--------+----------
 public.tablename |      0 | modified
(1 row)


doltgres=> select dolt_checkout('-b', 'b2');
         dolt_checkout
-------------------------------
 {0,"Switched to branch 'b2'"}
(1 row)

doltgres=> delete from tablename where pk=1;
DELETE 1

doltgres=> select dolt_commit('-Am', 'Delete row');)
            dolt_commit
------------------------------------
 {dlnqvbe32tlvbfn9pqos7bgihpgalt0e}
(1 row)

doltgres=> use doltgres/main;
SET

doltgres=> select * from dolt_status;
    table_name    | staged |  status
------------------+--------+----------
 public.tablename |      0 | modified
(1 row)

doltgres=> select dolt_merge('b2');
                        dolt_merge
-----------------------------------------------------------
 {dlnqvbe32tlvbfn9pqos7bgihpgalt0e,1,0,"merge successful"}
(1 row)

doltgres=> select * from dolt_status;
 table_name | staged | status
------------+--------+--------
(0 rows)