rust-pathauditor: actually split Windows shortname aliases at `~`
Right now, splitting with a max of 1 parts is useless.
Differential Revision: https://phab.mercurial-scm.org/D8211
rust-cpython: add `debug` module to expose debug information to Python
This will be mostly used in `debuginstall`.
Differential Revision: https://phab.mercurial-scm.org/D8225