index.reset is now partly implemented using python, but in fact it resorts to using git-read-tree to keep the stat information when merging one tree in. After all this is what needed to be implemented in python as well

Author: Byron

lib/git/ext/gitdb

@@ -1066,44 +1066,58 @@ def handle_stderr(proc, iter_checked_out_files):
 		# END paths handling
 		assert "Should not reach this point"
 
-	@post_clear_cache
 	@default_index
 	def reset(self, commit='HEAD', working_tree=False, paths=None, head=False, **kwargs):
-		"""
-		Reset the index to reflect the tree at the given commit. This will not
+		"""Reset the index to reflect the tree at the given commit. This will not
 		adjust our HEAD reference as opposed to HEAD.reset by default.
 
-		``commit``
+		:param commit:
 			Revision, Reference or Commit specifying the commit we should represent.
 			If you want to specify a tree only, use IndexFile.from_tree and overwrite
 			the default index.
 
-		``working_tree``
+		:param working_tree:
 			If True, the files in the working tree will reflect the changed index.
 			If False, the working tree will not be touched
 			Please note that changes to the working copy will be discarded without
 			warning !
 
-		``head``
+		:param head:
 			If True, the head will be set to the given commit. This is False by default,
 			but if True, this method behaves like HEAD.reset.
 
-		``**kwargs``
+		:param kwargs:
 			Additional keyword arguments passed to git-reset
 
-		Returns
-			self
-		"""
-		cur_head = self.repo.head
-		prev_commit = cur_head.commit
-
-		# reset to get the tree/working copy
-		cur_head.reset(commit, index=True, working_tree=working_tree, paths=paths, **kwargs)
-
-		# put the head back, possibly
-		if not head:
-			cur_head.reset(prev_commit, index=False, working_tree=False)
-		# END reset head
+		:return: self """
+		# currently we have to use the git command to set the working copy.
+		# Otherwise we can use our own one
+		if working_tree:
+			cur_head = self.repo.head
+			prev_commit = cur_head.commit
+			
+			cur_head.reset(commit, index=True, working_tree=working_tree, paths=paths, **kwargs)
+			
+			# put the head back, possibly
+			if not head:
+				self.repo.head.commit = prev_commit
+				
+			self._delete_entries_cache()
+		else:
+			# what we actually want to do is to merge the tree into our existing
+			# index, which is what git-read-tree does
+			new_inst = type(self).from_tree(self.repo, commit)
+			self.entries = new_inst.entries
+			self.write()
+			
+			#new_inst = type(self).new(self.repo, self.repo.commit(commit).tree)
+			#self.entries = new_inst.entries
+			#self.write()
+			# self.repo.git.update_index(ignore_missing=True, refresh=True, q=True)
+			
+			if head:
+				self.repo.head.commit = self.repo.commit(commit)
+		# END handle working tree
 
 		return self
 

lib/git/index/base.py

@@ -578,11 +578,6 @@ def make_paths():
 
 	@with_rw_repo('HEAD')
 	def test_compare_write_tree(self, rw_repo):
-		def write_tree(index):
-			tree_sha = index.write_tree().sha
-			return Tree(index.repo, tree_sha, 0, '')
-		# END git cmd write tree
-		
 		# write all trees and compare them
 		# its important to have a few submodules in there too
 		max_count = 25
@@ -593,8 +588,6 @@ def write_tree(index):
 			count += 1
 			index = rw_repo.index.reset(commit)
 			orig_tree = commit.tree
-			new_git_tree = write_tree(index)
-			assert new_git_tree == orig_tree
 			assert index.write_tree() == orig_tree
 		# END for each commit