Improve hglookup.py to directly map svn and hg commits to git

[brettcannon]

https://gist.github.com/brettcannon/f8d97c92b0df264cd4db008ffd32daf9

For the migration, hglookup.py just maps svn commits to svn.python.org and hg commits to hg.python.org. It would be nice to set it up so we have a mapping of svn and hg commits to git hashes and simply send everyone to python/cpython directly.

[soltysh]

I'm interested 😄

[brettcannon]

I've added you as a collaborator on this project. Once you have accepted the invite link feel free to assign this issue to yourself if you want.

[AA-Turner]

@brettcannon is this still relevant?

A