Avoid another tempdir content assumption in test

test_init was using tempfile.gettempdir() directly to get the
location where the hard-coded path repos/foo/bar.git would be used
to test repository creation with relative and absolute paths. That
reused the same location each time, and also assumed the directory
would be usable, which could fail due to previous runs or due to
the path being used separately from GitPython's tests. This commit
fixes that by using that path inside a temporary directory, known
at the start of the test to be empty.

Reorganizing the acquision and cleanup logic also has had the
effect of causing the test no longer to be skipped due to the logic
in git.util.rmtree due to the final cleanup attempt (after all
assertions). The directory is now successfully removed on Windows,
and the test passes on all platforms.

test/test_repo.py

@@ -41,7 +41,7 @@
     UnsafeProtocolError,
 )
 from git.repo.fun import touch
-from git.util import bin_to_hex, cygpath, join_path_native, rmfile, rmtree
+from git.util import bin_to_hex, cwd, cygpath, join_path_native, rmfile, rmtree
 from test.lib import TestBase, fixture, with_rw_directory, with_rw_repo
 
 
@@ -511,13 +511,11 @@ def write(self, b):
         repo.git.log(n=100, output_stream=TestOutputStream(io.DEFAULT_BUFFER_SIZE))
 
     def test_init(self):
-        prev_cwd = os.getcwd()
-        os.chdir(tempfile.gettempdir())
-        git_dir_rela = "repos/foo/bar.git"
-        del_dir_abs = osp.abspath("repos")
-        git_dir_abs = osp.abspath(git_dir_rela)
-        try:
-            # with specific path
+        with tempfile.TemporaryDirectory() as tdir, cwd(tdir):
+            git_dir_rela = "repos/foo/bar.git"
+            git_dir_abs = osp.abspath(git_dir_rela)
+
+            # With specific path
             for path in (git_dir_rela, git_dir_abs):
                 r = Repo.init(path=path, bare=True)
                 self.assertIsInstance(r, Repo)
@@ -527,7 +525,7 @@ def test_init(self):
 
                 self._assert_empty_repo(r)
 
-                # test clone
+                # Test clone
                 clone_path = path + "_clone"
                 rc = r.clone(clone_path)
                 self._assert_empty_repo(rc)
@@ -562,13 +560,6 @@ def test_init(self):
             assert not r.has_separate_working_tree()
 
             self._assert_empty_repo(r)
-        finally:
-            try:
-                rmtree(del_dir_abs)
-            except OSError:
-                pass
-            os.chdir(prev_cwd)
-        # END restore previous state
 
     def test_bare_property(self):
         self.rorepo.bare