This is a derived issue from bug 7353.

test.d
----
import std.stdio;
struct S
{
    static uint ci = 0;
    static uint di = 0;
    uint i;

    this(int x) { i = ci++; writeln("new: ", i); }
    this(this)  { i = ci++; writeln("copy ", i); }
    ~this()     { ++di;     writeln("del ", i); }

    S save3()
    {
        return this;
    }
}
void main()
{
    {
        auto s = S(1), t = S(1);
        assert(S.ci == 2);
        t = s.save3();
        assert(S.ci == 3);  // line 23
    }
}

Command line:
----
dmd -inline -run test.d

Output:
----
new: 0
new: 1
del 1
del 0
del 0
core.exception.AssertError@test(23): Assertion failure

Postblit is not called.