qgis - How to avoid the CRS Dialog when creating a vector layer memory?

I am trying to create a vector memory in a plugin. Basing on some examples,I was able to create a memory vector layer and to add it in QGis with : QgsMapLayer.instance().addMapLayer(myLayer,True)

But when the layer is added , QGis always displays the crs dialog to specify the crs of the layers

:

I tried to specify myself the crs with : layer.setCrs(QgsCoordinateReference(4326)) but it still shows me the crs dialog.

Do you have any ideas to how avoid this dialog ?