Status::OK() stringifies to: "OK " when put to an ostream but not when put to a StringBuilder.

There's a space because there might be a reason string, but there isn't one.

The output of Status.toString doesn't have the trailing space either.

When put to a StringBuilder, it also puts out the BSON extraInfo, so it's not expected that StringBuilder and ostream agree.

But the trailing space is at least suspicious.