delta-find: add a test checking various simple behavior There are enough work happening in this area that it is worth having a dedicated test for it. So far we add to small test checking that the "best" parent is picked as the delta base and that this behavior can be controlled during commit and unbundle.

rust-status: fix thread count ceiling This was forcing 16 threads instead of creating a ceiling, which is wrong when either the available parallelism of the platform is lower or when the user wants to set it explicitly (like we do in `run-tests.py`)

peer: pass the `path` to the statichttp peer We now have all peer able to receive and store a `path` object. Hooray.

peer: get the `path` object down to the sshpeer Same logic as the other peers.

logexchange: use the proper accessors to get the remote url There is an official method, let us use it. this will prevent a crash when the private attribute disappear.

peer: get the `path` object down to the httppeer One more peer with a path stored.

path: fix `url.copy` dropping the port The copy method have been wrong for a while, but the new code reveals it.

peer: pass the `path` object to `make_peer` We don't do anything with it yet, but we can start implementing it for each peer type starting now.

path: allow to copy a path while adjusting the url This will be used by `scheme` in the next changesets.

peer: store the path object used to build a peer from a repo This is the simplest case, we so starts with it.