fix the solution ordering for installation, by using the explicit topological ordering instead of the previous BFS.
fix the solution ordering for installation, by using the explicit topological ordering instead of the previous BFS.

Note : The topological one is indeed correct, but determine why the BFS was not !

Example :
cudf depends of extlib
1) upload extlib
2) upload cudf
3) install cudf : it proposes to install first cudf then extlib, which is wrong.

abate/opam,abate/opam