Fix d3.geo.circle Polygon exterior insertion.

d3.js

@@ -5634,12 +5634,11 @@
     }
     function clipLine(coordinates, context, winding) {
       if (!(n = coordinates.length)) return;
-      var point0 = rotate(coordinates[0]), inside = visible(point0), keepWinding = inside && winding != null, n;
+      var point0 = rotate(coordinates[0]), inside = visible(point0), keepWinding = winding != null, n;
       if (inside) context.moveTo(point0[0], point0[1]);
       for (var i = 1; i < n; i++) {
         var point1 = rotate(coordinates[i]), v = visible(point1);
         if (v !== inside) {
-          keepWinding = false;
           if (inside = v) {
             point0 = intersect(point1, point0);
             context.moveTo(point0[0], point0[1]);

src/geo/circle.js

@@ -163,14 +163,13 @@ function d3_geo_circleClip(degrees, rotate) {
     if (!(n = coordinates.length)) return;
     var point0 = rotate(coordinates[0]),
         inside = visible(point0),
-        keepWinding = inside && winding != null,
+        keepWinding = winding != null,
         n;
     if (inside) context.moveTo(point0[0], point0[1]);
     for (var i = 1; i < n; i++) {
       var point1 = rotate(coordinates[i]),
           v = visible(point1);
       if (v !== inside) {
-        keepWinding = false;
         if (inside = v) {
           // outside going in
           point0 = intersect(point1, point0);

test/geo/path-test.js

@@ -257,6 +257,18 @@ suite.addBatch({
           {type: "point", x: 170, y: 160},
           {type: "point", x: 170, y: 165}
         ]);
+      },
+      "Polygon": {
+        "inserts exterior along clip edge if polygon interior surrounds it": function(path) {
+          path({type: "Polygon", coordinates: [[[80, -80], [80, 80], [-80, 80], [-80, -80], [80, -80]]]});
+          var buffer = testContext.buffer();
+          assert.equal(buffer.filter(function(d) { return d.type === "moveTo"; }).length, 2);
+        },
+        "inserts exterior along clip edge if polygon exterior surrounds it": function(path) {
+          path({type: "Polygon", coordinates: [[[100, -80], [100, 80], [-100, 80], [-100, -80], [100, -80]]]});
+          var buffer = testContext.buffer();
+          assert.equal(buffer.filter(function(d) { return d.type === "moveTo"; }).length, 1);
+        }
       }
     }
   },