fix: Remove pygit2 dependency

On a few platforms (ask @peckto) the pygit2 dependency cannot be
installed with poetry, since the toolchain tries to build from source
and fails. Since we only use this library to detect the git root, let's
implement this with calling the Git binary instead. When git is not available,
then Git repos are not used for config discovery.

pyproject.toml

@@ -43,7 +43,6 @@ tabulate = ">=0.9"
 construct = "^2.10"
 msgspec = ">=0.11,<0.19"
 pydantic = "^2.0"
-pygit2 = "^1.10"
 platformdirs = ">=2.6,<5.0"
 exitcode = "^0.1.0"
 psutil = ">=5.9.4,<7.0.0"
@@ -83,7 +82,6 @@ plugins = [
 [[tool.mypy.overrides]]
 module = [
     "argcomplete",
-    "pygit2",
 ]
 ignore_missing_imports = true
 

src/gallia/config.py

@@ -3,12 +3,13 @@
 # SPDX-License-Identifier: Apache-2.0
 
 import os
+import shutil
+import subprocess
 import tomllib
 from pathlib import Path
 from typing import Any
 
 from platformdirs import user_config_path
-from pygit2 import discover_repository
 
 
 class Config(dict[str, Any]):
@@ -28,14 +29,16 @@ def get_value(self, key: str, default: Any | None = None) -> Any | None:
 
 
 def get_git_root() -> Path | None:
-    res = discover_repository(Path.cwd())
-    match res:
-        case str() as p:
-            return Path(p).parent
-        case None:
-            return None
-
-    raise ValueError(f"unexpected return from pygit2 {res}")
+    git_path = shutil.which("git")
+    if git_path is None:
+        return None
+    try:
+        p = subprocess.run(
+            [git_path, "rev-parse", "--show-toplevel"], capture_output=True, check=True
+        )
+    except subprocess.CalledProcessError:
+        return None
+    return Path(p.stdout.decode().strip())
 
 
 def get_config_dirs() -> list[Path]:

tests/pytest/test_config.py

@@ -3,19 +3,25 @@
 # SPDX-License-Identifier: Apache-2.0
 
 import os
+import shutil
+import subprocess
 from pathlib import Path
 
 import platformdirs
 import pytest
-from pygit2 import init_repository
 
 from gallia.config import get_config_dirs, load_config_file
 
 
+def init_repository(path: Path) -> None:
+    subprocess.run(["git", "init", path], check=True)
+
+
+@pytest.mark.skipif(shutil.which("git") is None, reason="git binary is not available")
 def test_config_discovery_git(tmp_path: Path) -> None:
     testrepo = tmp_path.joinpath("testrepo")
     testrepo.mkdir()
-    init_repository(str(testrepo))
+    init_repository(testrepo)
     os.chdir(testrepo)
 
     config_file = testrepo.joinpath("gallia.toml")