Format g bug ?

[Temtaime via Digitalmars-d-learn]

import std.stdio;

void main()
{
        writefln(`%.2g`, 3.11);
        writefln(`%.2f`, 3.11);

        writefln(`%.1g`, 3.11);
        writefln(`%.1f`, 3.11);
}


3.1
3.11
3
3.1

But expected

3.1
3.11
3.1
3.11