**Describe the bug**
Under certain conditions the equals comparison between String and Date yields the wrong result. Range Comparisons with greather-than-equals returns the correct result set.

**How to reproduce**
* Which ClickHouse server version to use: 21.2.5.5 (latest at the time of this issue)
* Which interface to use, if matters: HTTP (but should not matter)

```sql
CREATE TABLE default.myTable (
	myDay Date,
	myOrder Int32,
	someData String
) 
ENGINE = ReplacingMergeTree
PARTITION BY floor(toYYYYMMDD(myDay), -1)
ORDER BY (myOrder)
;

INSERT INTO default.myTable (myDay, myOrder) VALUES ('2021-01-01', 1);
INSERT INTO default.myTable (myDay, myOrder) VALUES ('2021-01-02', 2); // This row should be returned
INSERT INTO default.myTable (myDay, myOrder) VALUES ('2021-01-03', 3);

SELECT * FROM default.myTable mt
WHERE myDay = '2021-01-02';
```

**Expected behavior**
The last query in the example should yield the marked row. Instead it returns a empty result set.

There must be a connection to the used `PARTITION KEY`. The issue fails to reproduce as soon as I do any changes to the `PARTITION KEY` setting.

case FUNCTION_NOT_IN_SET:
        case FUNCTION_IN_SET:
        {
            buf << "(";
            print_wrapped_column(buf);
            buf << (function == FUNCTION_IN_SET ? " in " : " notIn ");
            if (!set_index)
                buf << "unknown size set";
            else
                buf << set_index->size() << "-element set";
            buf << ")";
            return buf.str();
        }
        case FUNCTION_IN_RANGE:
        case FUNCTION_NOT_IN_RANGE:
        {
            buf << "(";
            print_wrapped_column(buf);
            buf << (function == FUNCTION_NOT_IN_RANGE ? " not" : "") << " in " << range.toString();
            buf << ")";
            return buf.str();
        }
        case ALWAYS_FALSE:
            return "false";
        case ALWAYS_TRUE:
            return "true";
    }
    __builtin_unreachable();
}
bool KeyCondition::alwaysUnknownOrTrue() const