upsert -- match null?

[davidAtInleague]

hey upsert is great; I ran into the following using it, on the MSSQL grammar:

getInstance("queryBuilder@qb").from("rmme_foo").upsert(
	values = {a: 1, b: {value: "", null: true}, c: "some new string value"},
	target = ["a","b"],
	update = ["c"]
)

generates:

MERGE [rmme_foo] AS [qb_target] USING (VALUES (1, null, 'some new string value')) AS [qb_src] ([A], [B], [C]) ON
    [qb_target].[a] = [qb_src].[a] AND
    [qb_target].[b] = [qb_src].[b]  /* <------ this */
WHEN MATCHED THEN UPDATE SET [c] = [qb_src].[c]
WHEN NOT MATCHED BY TARGET THEN INSERT ([A], [B], [C]) VALUES ([A], [B], [C]);

the line marked <------- this should probably be [qb_target].[b] is null, otherwise it never matches (since null never equals null)