index.write_tree: fixed bug that would cause the written tree not to contain any of our changes entries as it would in fact write a possibly cached tree stored in our extension data.It was solved by simply ignoring that extension data when writing the index for tree creation. A test was added for this as well

Author: Byron

lib/git/diff.py

@@ -39,6 +39,7 @@ def diff(self, other=Index, paths=None, create_patch=False, **kwargs):
 		``other``
 			Is the item to compare us with. 
 			If None, we will be compared to the working tree.
+			If Treeish, it will be compared against the respective tree
 			If Index ( type ), it will be compared against the index.
 			It defaults to Index to assure the method will not by-default fail
 			on bare repositories.

lib/git/index.py

@@ -191,7 +191,7 @@ def from_base(cls, base):
 			Instance of type BaseIndexEntry
 		"""
 		time = struct.pack(">LL", 0, 0)
-		return IndexEntry((base.mode, base.sha, base.stage, base.path, time, time, 1, 1, 1, 1, 0))
+		return IndexEntry((base.mode, base.sha, base.stage, base.path, time, time, 0, 0, 0, 0, 0))
 
 	@classmethod
 	def from_blob(cls, blob):
@@ -352,6 +352,10 @@ def _read_from_stream(self, stream):
 
 		# the footer contains extension data and a sha on the content so far
 		# Keep the extension footer,and verify we have a sha in the end
+		# Extension data format is: 
+		# 4 bytes ID
+		# 4 bytes length of chunk
+		# repeated 0 - N times
 		self._extension_data = stream.read(~0)
 		assert len(self._extension_data) > 19, "Index Footer was not at least a sha on content as it was only %i bytes in size" % len(self._extension_data)
 
@@ -733,9 +737,23 @@ def write_tree(self, missing_ok=False):
 		index_path = self._index_path()
 		tmp_index_mover = _TemporaryFileSwap(index_path)
 
+		# IMPORTANT: If we have TREE extension data, it will actually 
+		# ignore the index and write the stored tree instead. Hence we 
+		# temporarily forget about it, and in fact I don't know what git 
+		# uses it for
+		stored_ext_data = None
+		if self._extension_data and self._extension_data[:4] == 'TREE':
+			stored_ext_data = self._extension_data
+			self._extension_data = ''
+		# END extension data special handling
+		
 		self.write(index_path)
 		tree_sha = self.repo.git.write_tree(missing_ok=missing_ok)
 
+		if stored_ext_data:
+			self._extension_data = stored_ext_data
+		# END reset stored exstension data
+		
 		return Tree(self.repo, tree_sha, 0, '')
 
 	def _process_diff_args(self, args):

test/git/test_index.py

@@ -14,7 +14,6 @@
 import shutil
 from stat import *
 
-
 class TestTree(TestBase):
 
 	def __init__(self, *args):
@@ -464,13 +463,18 @@ def mixed_iterator():
 		full_index_entry = IndexEntry.from_base(BaseIndexEntry((0120000, entries[0].sha, 0, entries[0].path)))
 		entry_key = index.get_entries_key(full_index_entry)
 		index.reset(new_commit)
+		
 		assert entry_key not in index.entries
 		index.entries[entry_key] = full_index_entry
 		index.write()
 		index.update()	# force reread of entries
 		new_entry = index.entries[entry_key]
 		assert S_ISLNK(new_entry.mode)
 
+		# a tree created from this should contain the symlink
+		tree = index.write_tree(True)
+		assert fake_symlink_relapath in tree
+		
 		# checkout the fakelink, should be a link then
 		assert not S_ISLNK(os.stat(fake_symlink_path)[ST_MODE])
 		os.remove(fake_symlink_path)