tests: move non-collapse test out of test-rebase-collapse The test case was added in 76630fbbf4fa (test-rebase-collapse: Add test for rebase regression introduced in 12309c09d19a, 2012-01-23). I think `hg rebase --collapse` was involved in either the regression or in the fix that caused the regression, but the test that was added doesn't use `--collapse`, so it doesn't seem to belong in test-rebase-collapse.t. The test case is about copies, so I moved it to test-rebase-rename.t. Differential Revision: https://phab.mercurial-scm.org/D7968

debugcommands: add Python implementation to debuginstall This seems like a useful detail to print. Differential Revision: https://phab.mercurial-scm.org/D7979

run-tests: remove --py3-warnings This Python 2 only mode was to help Python 2 alert when doing things not supported on Python 3. Now that we have test coverage with Python 3, I don't think we need it. Differential Revision: https://phab.mercurial-scm.org/D7978

rust-node: binary Node ID and conversion utilities The choice of type makes sure that a `Node` has the exact wanted size. We'll use a different type for prefixes. Added dependency: hexadecimal conversion relies on the `hex` crate. The fact that sooner or later Mercurial is going to need to change its hash sizes has been taken strongly in consideration: - the hash length is a constant, but that is not directly exposed to callers. Changing the value of that constant is the only thing to do to change the hash length (even in unit tests) - the code could be adapted to support several sizes of hashes, if that turned out to be useful. To that effect, only the size of a given `Node` is exposed in the public API. - callers not involved in initial computation, I/O and FFI are able to operate without a priori assumptions on the hash size. The traits `FromHex` and `ToHex` have not been directly implemented, so that the doc-comments explaining these restrictions would stay really visible in `cargo doc` Differential Revision: https://phab.mercurial-scm.org/D7788