Replace GIT_VERSION constant with lazy function

copier/vcs.py

@@ -20,16 +20,10 @@ def get_git():
     return local["git"]
 
 
-try:
-    GIT_VERSION = Version(re.findall(r"\d+\.\d+\.\d+", get_git()("version"))[0])
-except OSError:
-    import warnings
-
-    warnings.warn(
-        "git command not found, some functionality might not work", UserWarning
-    )
+def get_git_version():
+    git = get_git()
 
-    GIT_VERSION = None  # type: ignore
+    return Version(re.findall(r"\d+\.\d+\.\d+", git("version"))[0])
 
 
 GIT_PREFIX = ("git@", "git://", "git+", "https://github.com/", "https://gitlab.com/")
@@ -161,10 +155,11 @@ def clone(url: str, ref: OptStr = None) -> str:
             Reference to checkout. For Git repos, defaults to `HEAD`.
     """
     git = get_git()
+    git_version = get_git_version()
     location = mkdtemp(prefix=f"{__name__}.clone.")
     _clone = git["clone", "--no-checkout", url, location]
     # Faster clones if possible
-    if GIT_VERSION >= Version("2.27"):
+    if git_version >= Version("2.27"):
         url_match = re.match("(file://)?(.*)", url)
         if url_match is not None:
             file_url = url_match.groups()[-1]

tests/test_vcs.py

@@ -11,7 +11,7 @@
 
 from copier import Worker, run_copy, run_update
 from copier.errors import ShallowCloneWarning
-from copier.vcs import GIT_VERSION, checkout_latest_tag, clone, get_repo
+from copier.vcs import get_git_version, checkout_latest_tag, clone, get_repo
 
 
 def test_get_repo() -> None:
@@ -93,7 +93,7 @@ def test_shallow_clone(tmp_path: Path, recwarn: pytest.WarningsRecorder) -> None
     git("clone", "--depth=2", "https://github.com/copier-org/autopretty.git", src_path)
     assert Path(src_path, "README.md").exists()
 
-    if GIT_VERSION >= Version("2.27"):
+    if get_git_version() >= Version("2.27"):
         with pytest.warns(ShallowCloneWarning):
             local_tmp = clone(str(src_path))
     else: