Fix remaining old Commit_ish annotations in git.refs

(This also improves the sorting of imports where they are already
being changed, and fixes a typo in a comment.)

Author: EliahKagan

git/refs/head.py

@@ -15,14 +15,14 @@
 
 # typing ---------------------------------------------------
 
-from typing import Any, Sequence, Union, TYPE_CHECKING
+from typing import Any, Sequence, TYPE_CHECKING, Union
 
-from git.types import PathLike, Old_commit_ish
+from git.types import Commit_ish, PathLike
 
 if TYPE_CHECKING:
-    from git.repo import Repo
     from git.objects import Commit
     from git.refs import RemoteReference
+    from git.repo import Repo
 
 # -------------------------------------------------------------------
 
@@ -62,7 +62,7 @@ def orig_head(self) -> SymbolicReference:
 
     def reset(
         self,
-        commit: Union[Old_commit_ish, SymbolicReference, str] = "HEAD",
+        commit: Union[Commit_ish, SymbolicReference, str] = "HEAD",
         index: bool = True,
         working_tree: bool = False,
         paths: Union[PathLike, Sequence[PathLike], None] = None,
@@ -99,7 +99,7 @@ def reset(
         if index:
             mode = "--mixed"
 
-            # Tt appears some git versions declare mixed and paths deprecated.
+            # It appears some git versions declare mixed and paths deprecated.
             # See http://github.com/Byron/GitPython/issues#issue/2.
             if paths:
                 mode = None

git/refs/reference.py

@@ -1,24 +1,20 @@
 # This module is part of GitPython and is released under the
 # 3-Clause BSD License: https://opensource.org/license/bsd-3-clause/
 
-from git.util import (
-    LazyMixin,
-    IterableObj,
-)
+from git.util import IterableObj, LazyMixin
 from .symbolic import SymbolicReference, T_References
 
-
 # typing ------------------------------------------------------------------
 
-from typing import Any, Callable, Iterator, Type, Union, TYPE_CHECKING
-from git.types import Old_commit_ish, PathLike, _T
+from typing import Any, Callable, Iterator, TYPE_CHECKING, Type, Union
+
+from git.types import AnyGitObject, PathLike, _T
 
 if TYPE_CHECKING:
     from git.repo import Repo
 
 # ------------------------------------------------------------------------------
 
-
 __all__ = ["Reference"]
 
 # { Utilities
@@ -81,7 +77,7 @@ def __str__(self) -> str:
     # @ReservedAssignment
     def set_object(
         self,
-        object: Union[Old_commit_ish, "SymbolicReference", str],
+        object: Union[AnyGitObject, "SymbolicReference", str],
         logmsg: Union[str, None] = None,
     ) -> "Reference":
         """Special version which checks if the head-log needs an update as well.