Fix commented *.py names at the top of modules

A number of them were incorrect, due to how files were renamed, and
code moved between them, over time. Some were corrected earlier,
and most of the rest are corrected here.

Not all modules have these at all. This does not add any to modules
that don't have them. It only fixes them where present but wrong.

git/index/base.py

@@ -1,4 +1,4 @@
-# index.py
+# base.py
 # Copyright (C) 2008, 2009 Michael Trier (mtrier@gmail.com) and contributors
 #
 # This module is part of GitPython and is released under

git/objects/tag.py

@@ -1,4 +1,4 @@
-# objects.py
+# tag.py
 # Copyright (C) 2008, 2009 Michael Trier (mtrier@gmail.com) and contributors
 #
 # This module is part of GitPython and is released under

git/repo/base.py

@@ -1,4 +1,4 @@
-# repo.py
+# base.py
 # Copyright (C) 2008, 2009 Michael Trier (mtrier@gmail.com) and contributors
 #
 # This module is part of GitPython and is released under

git/util.py

@@ -1,4 +1,4 @@
-# utils.py
+# util.py
 # Copyright (C) 2008, 2009 Michael Trier (mtrier@gmail.com) and contributors
 #
 # This module is part of GitPython and is released under

test/test_db.py

@@ -1,4 +1,4 @@
-# test_repo.py
+# test_db.py
 # Copyright (C) 2008, 2009 Michael Trier (mtrier@gmail.com) and contributors
 #
 # This module is part of GitPython and is released under

test/test_docs.py

@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-# test_git.py
+# test_docs.py
 # Copyright (C) 2008, 2009 Michael Trier (mtrier@gmail.com) and contributors
 #
 # This module is part of GitPython and is released under