t = db.array1
t.drop()

x = { a : [ 1 , 2 ] };

t.save( { a : [ [1,2] ] } );
assert.eq( 1 , t.find( x ).count() , "A" );

t.save( x );
delete x._id;
assert.eq( 2 , t.find( x ).count() , "B" );

t.ensureIndex( { a : 1 } );
assert.eq( 2 , t.find( x ).count() , "C" ); // TODO SERVER-146