Broken GIT_SORT_TIME ?

This is a script to reproduce the behavior I'm seeing:

#!/usr/bin/env python

import tempfile
import time
import os

import pygit2

path = tempfile.mkdtemp(prefix='pygit2_test_')
repo = pygit2.init_repository(path)

author = pygit2.Signature('Alice Author', 'alice@authors.tld')
committer = pygit2.Signature('Cecil Committer', 'cecil@committers.tld')

# Commit #1

 # Create a file in that git repo
with open(os.path.join(path, 'sources'), 'w') as stream:
    stream.write('foo\n bar')
repo.index.add('sources')
repo.index.write()

parents = []
# Commits the files added
tree = repo.index.write_tree()
print(repo.create_commit(
    'refs/heads/master',  # the name of the reference to update
    author,
    committer,
    'Commit #1',
    # binary string representing the tree object ID
    tree,
    # list of binary strings representing parents of the new commit
    parents,
))
commit1 = repo.revparse_single('HEAD')
time.sleep(0.1)

# Commit #2

parents = [commit1.oid.hex]

subfolder = os.path.join('folder1', 'folder2')
os.makedirs(os.path.join(path, subfolder))
# Create a file in that git repo
with open(os.path.join(path, subfolder, 'file'), 'w') as stream:
    stream.write('foo\n bar\nbaz')
repo.index.add(os.path.join(subfolder, 'file'))
repo.index.write()

# Commits the files added
tree = repo.index.write_tree()
print(repo.create_commit(
    'refs/heads/master',  # the name of the reference to update
    author,
    committer,
    'Commit #2',
    # binary string representing the tree object ID
    tree,
    # list of binary strings representing parents of the new commit
    parents
))
commit2 = repo.revparse_single('HEAD')
time.sleep(0.1)


# Commit #3

parents = [commit2.oid.hex]

# Update the sources file
with open(os.path.join(path, 'sources'), 'w') as stream:
    stream.write('foo\n bar\nbaz!')
repo.index.add('sources')
repo.index.write()

# Commits the files added
tree = repo.index.write_tree()
print(repo.create_commit(
    'refs/heads/master',  # the name of the reference to update
    author,
    committer,
    'Commit #3',
    # binary string representing the tree object ID
    tree,
    # list of binary strings representing parents of the new commit
    parents
))
commit3 = repo.revparse_single('HEAD')


print('')
main_walker = repo.walk(commit3.oid.hex, pygit2.GIT_SORT_TIME)
commits_msgs = []
while 1:
    try:
        com = main_walker.next()
        print(com.message)
        print(com.oid.hex)
    except StopIteration:
        break

It gives me the following output:

7335ffcfdb2039a9631ef5c891ec6a12feaeb342
50ea7d4691ee78b60323ac1d4174a6609190fbaf
47e61d2eaa8c5d3d1562475a43aa99c0e7fb9b8a

Commit #3
47e61d2eaa8c5d3d1562475a43aa99c0e7fb9b8a
Commit #1
7335ffcfdb2039a9631ef5c891ec6a12feaeb342
Commit #2
50ea7d4691ee78b60323ac1d4174a6609190fbaf

The first three lines are the commit as they are committed.
The following lines are the commit message and hash as repo.walk(commit3, pygit2.GIT_SORT_TIME) is returning them.

Something looks broken to me :)

Start by running the reproduction script and inspecting the pygit2 binding for repo.walk with GIT_SORT_TIME. Compare the observed order with the documented sorting behavior and existing walker tests; done means the ordering is corrected or the behavior is clearly documented with a regression test.