This is true, but if it is documented it is still sufficiently oddball to be useless. Consider:

    Midnight UTC, timezone EST:  True
    Midnight UTC, timezone CET:  False
    Midnight UTC, timezone CST:  True
    Midnight UTC, timezone WIT:  False
    Midnight UTC, timezone PST:  True

Now the problem here is that it may well be documented but it is in fact unsafe to rely on in any context. The behavior is thus irretrievably broken, documented or not. It isn't even expert-friendly. The behavior, documented or not, is irretrievably broken. After all timezones west of GMT will never have false times.

If there is a use case for this behavior, I sure can't see it. Unless you like bugs appearing when you change timezones.