__init__: don't run refresh on import

doc/source/changes.rst

@@ -2,6 +2,19 @@
 Changelog
 =========
 
+4.0.0
+=====
+
+GitPython will no longer throw an ImportError when no git executable can
+be found at import time. Instead, errors are deferred until the first
+attempt at using it. Consumers with special handling for
+the old ImportError behaviour should instead call `git.refresh` and handle
+GitCommandNotFoundErrors themselves.
+
+See the following for all changes.
+https://github.com/gitpython-developers/GitPython/releases/tag/4.0.0
+
+
 3.1.45
 ======
 

git/__init__.py

@@ -292,9 +292,4 @@ def refresh(path: Optional[PathLike] = None) -> None:
     GIT_OK = True
 
 
-try:
-    refresh()
-except Exception as _exc:
-    raise ImportError("Failed to initialize: {0}".format(_exc)) from _exc
-
 # } END initialize git executable path

git/cmd.py

@@ -857,7 +857,7 @@ def refresh(cls, path: Union[None, PathLike] = None) -> bool:
                     if mode in warn:
                         _logger.critical(err)
                     else:
-                        raise ImportError(err)
+                        raise GitCommandNotFound(new_git, err)
                 else:
                     err = dedent(
                         """\
@@ -1575,6 +1575,8 @@ def _call_process(
             default (especially ``as_process = False``, ``stdout_as_string = True``) and
             return :class:`str`.
         """
+        if not self.GIT_PYTHON_GIT_EXECUTABLE:
+            self.refresh()
         # Handle optional arguments prior to calling transform_kwargs.
         # Otherwise these'll end up in args, which is bad.
         exec_kwargs = {k: v for k, v in kwargs.items() if k in execute_kwargs}

test/__init__.py

@@ -2,3 +2,7 @@
 #
 # This module is part of GitPython and is released under the
 # 3-Clause BSD License: https://opensource.org/license/bsd-3-clause/
+#
+import git
+
+git.refresh()

test/test_git.py

@@ -434,7 +434,7 @@ def test_initial_refresh_from_bad_git_path_env_error(self, case):
             Git.GIT_PYTHON_GIT_EXECUTABLE = None  # Simulate startup.
 
             with mock.patch.dict(os.environ, env_vars):
-                with self.assertRaisesRegex(ImportError, r"\ABad git executable.\n"):
+                with self.assertRaisesRegex(GitCommandNotFound, r"Bad git executable."):
                     refresh()
 
     def test_initial_refresh_from_good_absolute_git_path_env(self):