tig recently updated it's bash-completion making it depend on __git-complete from git.
Becase __git-complete is not automatically sourced tig bash completion fails.
Also this PR makes tig completion load on-demand.
init an unstable version since the tagged release wouldn't work on my
machine (infinite loop).
Practical tool to fetch several repositories at the same time, see their
status etc.
Disabled for darwin because of CI error "SIGILL: illegal instruction".
git-cinnabar calls into Mercurial as a library, so we make use the
same version of Python as Mercurial.
Support for Python 3 is an experimental feature in git-cinnabar, but
we unconditionally use it here because:
* Mercurial in Nixpkgs only supports Python 3.
* git-cinnabar touches a network, and for that purpose it's good to
use a version of Python that is going to get security updates.
###### Motivation for this change
Update to latest upstream version
###### Things done
* [ ] Tested using sandboxing ([nix.useSandbox](http://nixos.org/nixos/manual/options.html#opt-nix.useSandbox) on NixOS, or option `sandbox` in [`nix.conf`](http://nixos.org/nix/manual/#sec-conf-file) on non-NixOS linux)
* Built on platform(s)
* [x] NixOS
* [ ] macOS
* [ ] other Linux distributions
* [ ] Tested via one or more NixOS test(s) if existing and applicable for the change (look inside [nixos/tests](https://github.com/NixOS/nixpkgs/blob/master/nixos/tests))
* [ ] Tested compilation of all pkgs that depend on this change using `nix-shell -p nix-review --run "nix-review wip"`
* [x] Tested execution of all binary files (usually in `./result/bin/`)
* [ ] Determined the impact on package closure size (by running `nix path-info -S` before and after)
* [ ] Ensured that relevant documentation is up to date
* [x] Fits [CONTRIBUTING.md](https://github.com/NixOS/nixpkgs/blob/master/.github/CONTRIBUTING.md).
###### Notify maintainers
cc @worldofpeace @tfc @jtraue
In 6733ece `-DUSE_HTTP_PARSER=system` was introduced, which does not seem
to work with this fork. So instead fallback to the `builtin`.
Also sync with upstream cmake flags.
See inline comment; this does not build on Hydra and either requires custom
patching or a new release from upstream before it will build.
Note that we can still recompute the `cargoSha256` for #79975; the package
is broken in the identical way.
Maximilian Bosch