rebase: calculate obsolescense-related info earlier My goal is to use `rewriteutil.precheck()` in the rebase code. Since rebase does its own handling of divergent commits (it skips them instead of erroring out), we need to have divergence-causing commits filtered out early. This patch helps prepare for that. Differential Revision: https://phab.mercurial-scm.org/D10247

rebase: let _handleskippingobsolete(self) read directly from self The function already has `self` as an argument, so there's no need to pass data from `self` into it. Differential Revision: https://phab.mercurial-scm.org/D10246

tests: test divergence created during interrupted rebase If a rebase runs into conflicts and the user somehow rewrites an unrebased commit in the rebase set while the rebase is interrupted, continuing it might result in divergence. It turns out that we decide to skip the commit. That seems to make sense, but it wasn't obvious to me that that's what we should do. Either way, this patch adds a test case for the current behavior. Differential Revision: https://phab.mercurial-scm.org/D10256

tests: split up test-rebase-obsolete.t in four pieces The test case took 42 seconds to run the test before this patch and 12 seconds after (wall time, of course). Differential Revision: https://phab.mercurial-scm.org/D10255

path: error out if the `path://` reference point to an unknown path Differential Revision: https://phab.mercurial-scm.org/D10265

path: forbid chaining `path://` definitions To have `path://xxx` referencing paths that use `path://` too, we need to analyze dependencies to initialize them in the right order (and to detect cycle). I don't want to deal with that right now, so I just disallow it for now. Differential Revision: https://phab.mercurial-scm.org/D10264

path: introduce a `path://` syntax to reference other path name This make it easier for a path to reuse the same location of another path with different parameter. This is useful to create path "alias" with common config option. This will become very useful to create path that reference a list of other path. This changeset focus on implemented the basic feature, future changesets will deal with various error management (and associated testing). Differential Revision: https://phab.mercurial-scm.org/D10263

path: extract sub-option logic into its own method We will need to re-use this logic for `path://` so we first extract it into its own method. Differential Revision: https://phab.mercurial-scm.org/D10262

path: extract the path validation logic into its own submethod We will need to re-use this logic for `path://` so we first extract it into its own method. Differential Revision: https://phab.mercurial-scm.org/D10261

path: move handling of "default" (*) suboptions value inside __init__ With the introduction of `path://` scheme the handling of default value will need to be subtler. We do simple code movement first to clarify the future changes. Differential Revision: https://phab.mercurial-scm.org/D10260