git: pass `id` attribute of `pygit2.Tree` object
`pygit2`'s Repository object expects an instance of `Oid`
to return the corresponding object, instead of the object
itself.
After this change and D9062, `hg commit -i` seems to work,
unless it hits a case folding assertion (ie trying to add
a file like `README.md`).
Differential Revision: https://phab.mercurial-scm.org/D9068
{
"version": 1,
"project": "mercurial",
"project_url": "https://mercurial-scm.org/",
"repo": "..",
"branches": ["default", "stable"],
"environment_type": "virtualenv",
"show_commit_url": "https://www.mercurial-scm.org/repo/hg/rev/",
"benchmark_dir": "benchmarks",
"env_dir": "../.asv/env",
"results_dir": "../.asv/results",
"html_dir": "../.asv/html"
}