toStartOfMonth() bug #2327
Description
This function returns 0000-00-00 for any date in January, 1970:
:) SELECT toStartOfMonth(toDate('1970-01-01'));
┌─toStartOfMonth(toDate(\'1970-01-01\'))─┐
│ 0000-00-00 │
└────────────────────────────────────────┘
:) SELECT toStartOfMonth(toDate('1970-02-01'));
┌─toStartOfMonth(toDate(\'1970-02-01\'))─┐
│ 1970-02-01 │
└────────────────────────────────────────┘
This was from Clickhouse version 1.1.54378.