Do not keep iterating if the curve was reduced to a point.

src/path/Curve.js

@@ -1152,7 +1152,7 @@ new function() { // Scope for methods that require numerical integration
                         curve1, t1, Curve.evaluate(v1, t1, 0),
                         curve2, t2, Curve.evaluate(v2, t2, 0));
             }
-        } else { // Iterate
+        } else if (tDiff > 0) { // Iterate
             addCurveIntersections(v2, v1, curve2, curve1, locations, include,
                     uMin, uMax, tMinNew, tMaxNew, tDiff, !reverse, ++recursion);
         }