Extern/scope issue

[DLearner via Digitalmars-d-learn]

'Testmain' imports module 'testmod'.
Both are shown below.
I expected 1,1,2,2.
I got 1,0,2,1 - which speaks to scope/extern misunderstanding

Any ideas?
Best regards

Testmain:

int xvar;
import testmod;
void main() {
   import std.stdio;

   writeln("Entering: main");
   xvar = 1;
   writeln("xvar=", xvar);
   testsub();
   writeln("xvar=", xvar);

   writeln("Leaving: main");
}

Testmod:

void testsub() {

   extern(D) int xvar;
   import std.stdio;

   writeln("Entering: testsub");
   writeln("xvar=", xvar);
   xvar = 2;
   writeln("xvar=", xvar);
   writeln("Leaving: testsub");
}