reduce propagate complexity from O(n2) to O(n) (#3528)
reduce propagate complexity from O(n2) to O(n) (#3528)

* reduce propagate complexity from O(n2) to O(n)

* fixed sorted py2to3 issue

memsharded/conan,memsharded/conan,conan-io/conan,conan-io/conan,memsharded/conan,memsharded/conan,conan-io/conan,luckielordie/conan,luckielordie/conan