Leaflet Circle radius changing dependant on y/lng coords - leaflet

Question

I am using mapbox/leaflet to display a picture of a human body rather than a regular map.
I am using leaflet draw and I need to be able to create a circle and move it around while maintaining its radius. However, when I move it towards the bottom of the map/screen, the size increases exponentialy. I want it to stay the same size.
I assume it's something to do with projection or CRS but I'm not sure what to do to stop it.
My code is :
var mapMinZoom = 0;
var mapMaxZoom = 4;
var map = L.map('map', {
maxZoom: mapMaxZoom,
minZoom: mapMinZoom,
crs: L.CRS.Simple,
noWrap: true,
continuousWorld: true
}).setView([0, 0], mapMaxZoom);
var mapBounds = new L.LatLngBounds(
map.unproject([0, 3840], mapMaxZoom),
map.unproject([4096, 0], mapMaxZoom));
map.fitBounds(mapBounds);
L.tileLayer('/tiles/{z}/{x}/{y}.png', {
minZoom: mapMinZoom, maxZoom: mapMaxZoom,
bounds: mapBounds,
attribution: 'Rendered with MapTiler',
noWrap: true,
continuousWorld: true
}).addTo(map);
var touches;
var featureGroup = L.featureGroup().addTo(map);
var drawControl = new L.Control.Draw({
edit: {
featureGroup: featureGroup
}
}).addTo(map);
map.on('draw:created', function (e) {
featureGroup.addLayer(e.layer);
});
Any ideas? I don't need to use leaflet draw, just the L.circle would do, but it has the same issue.
Gif of issue here :

Answer 1

Turns out there are a load of todos in the leaflet 0.7 code... including this little gem :
// TODO Earth hardcoded, move into projection code!
_getLatRadius: function () {
return (this._mRadius / 40075017) * 360;
},
_getLngRadius: function () {
return this._getLatRadius() / Math.cos(L.LatLng.DEG_TO_RAD * this._latlng.lat);
},
Updated to 0.8Dev and it has all been fixed!