hgext/git/gitutil.py

rust: do a clippy pass

This is the result of running `cargo clippy` on hg-core/hg-cpython and fixing
the lints that do not require too much code churn (and would warrant a separate
commit/complete refactor) and only come from our code (a lot of warnings in
hg-cpython come from `rust-cpython`).

Most of those were good lints, two of them was the linter not being smart
enough (or compiler to get up to `clippy`'s level depending on how you see it).

Maybe in the future we could have `clippy` be part of the CI.

Differential Revision: https://phab.mercurial-scm.org/D8635

"""utilities to assist in working with pygit2"""
from __future__ import absolute_import

from mercurial.node import bin, hex, nullid

from mercurial import pycompat

pygit2_module = None


def get_pygit2():
    global pygit2_module
    if pygit2_module is None:
        try:
            import pygit2 as pygit2_module

            pygit2_module.InvalidSpecError
        except (ImportError, AttributeError):
            pass
    return pygit2_module


def togitnode(n):
    """Wrapper to convert a Mercurial binary node to a unicode hexlified node.

    pygit2 and sqlite both need nodes as strings, not bytes.
    """
    assert len(n) == 20
    return pycompat.sysstr(hex(n))


def fromgitnode(n):
    """Opposite of togitnode."""
    assert len(n) == 40
    if pycompat.ispy3:
        return bin(n.encode('ascii'))
    return bin(n)


nullgit = togitnode(nullid)