py3: force bytestr conversion of "reason" in scmutil.callcatch() For instance, reason may be an InvalidURL as shown in added test.

tests-pure: fixing test-parseindex2 This is a followup to D7603 (49fa0b31ee1d) which broke the tests for pure Python implementation. There are two divergences between pure and C implementations: - the pure implementation would accept only -1 as slice end, whereas C accepts both -1 and len(index) - in pure Python, `headrevs` is provided by revlog.py, not by the index. Differential Revision: https://phab.mercurial-scm.org/D7707

rust-index: add a function to convert PyObject index for hg-core Function in hg-core need something implementing the `Graph` trait. Right now, the `hg-cpython` entry points directly turn the PyObject passed as argument into a `cindex::Index`. However, if we start having the option to use an Index in Rust, we need to dispatch between the different possible PyObject we could receive. So move the "duplicate" call into a unified function. When time come. It will be easy to update the logic of all interface when the time come. Differential Revision: https://phab.mercurial-scm.org/D7653

test: extract some generic data and utility from test-rust-ancestor.py We will reuse this for more tests related to revlog index. In pratice this series of changesets add an index implementation provided from Rust and we want to be able to test it. Differential Revision: https://phab.mercurial-scm.org/D7652

patch: fix header.__repr__() to not have `b''` prefixes in file names Spotted by Denis Laxalde. Differential Revision: https://phab.mercurial-scm.org/D7695

cmdutil: allow native string as input to check_at_most_one_arg() We seem to always convert **opts args to use bytes as keys early on in Mercurial core, but I'm not sure we have good reason to do that, and not all extensions do that. It's therefore helpful to be able to pass in a native string to check_at_most_one_arg(). Differential Revision: https://phab.mercurial-scm.org/D7699