rust-discovery: use while loop instead of match + break This looks slightly nicer.

rust-discovery: remove useless extern crate

transplant: added support for --stop flag This adds fuctionality for `--stop` flag to `transplant`. A new method `stop` is added to `transplanter` class containing logic to abort transplant. Tests are updated as shown. Differential Revision: https://phab.mercurial-scm.org/D6695

unshelve: abort on using --keep and --interactive together I am working on making interactive mode support `--keep` flag. Until we support the usage of `--interactive` and `--keep` together, let us abort on it. Differential Revision: https://phab.mercurial-scm.org/D6699

config: add experimental argument to the config registrar Until now, there are almost 28 config items which are considered as `experimental` but, not present in the `experimental` section of the registrar. This patch adds an `experimental` argument to the config registrar to mark such config items. Differential Revision: https://phab.mercurial-scm.org/D6728 Differential Revision: https://phab.mercurial-scm.org/D6746

tests: split joint repo/changelog fake into one for each type I'm just not comfortable with fakes that get overloaded for multiple types: too often it gets out of hand and becomes difficult to trace. Differential Revision: https://phab.mercurial-scm.org/D6725

fix: pass line ranges as value instead of callback The callback no longer takes any arguments from the inner function, so we might as well call it sooner and pass the value instead. Note the value still needs to be recomputed every iteration to account for the previous iteration's changes to the file content. Differential Revision: https://phab.mercurial-scm.org/D6727

fix: correctly parse the :metadata subconfig It's being handled as a string instead of a bool, though the thruthiness of the string makes the feature still essentially work. Added a regression test. Differential Revision: https://phab.mercurial-scm.org/D6726

fix: allow tools to use :linerange, but also run if a file is unchanged The definition of "unchanged" here is subtle, because pure deletion diff hunks are ignored. That means this is different from using the --whole flag. This change allows you to configure, for example, a code formatter that: 1. Formats specific line ranges if specified via flags 2. Does not format the entire file when there are no line ranges provided 3. Performs some other kind of formatting regardless of provided line ranges This sounds a little far fetched, but it is meant to address a specific corner case encountered in Google's use of the fix extension. The default behavior is kept because it exists to prevent mistakes that could erase uncommitted changes. Differential Revision: https://phab.mercurial-scm.org/D6723

rust-dirstate: call rust dirstatemap from Python Since Rust-backed Python classes cannot be used as baseclasses (for rust-cpython anyway), we use composition rather than inheritance. This also allows us to keep the IO operations in the Python side, removing (for now) the need to rewrite VFS in Rust, which would be a heavy undertaking. Differential Revision: https://phab.mercurial-scm.org/D6634