Remove SortMode from list_commits

The current version of libgit2 available (0.26.3) has different behavior
with SortMode.TIME. It works correctly when left at the default (which
is also how the rawhide version works).

src/pylorax/api/recipes.py

@@ -734,7 +734,6 @@ def list_commits(repo, branch, filename, limit=0):
     :raises: Can raise errors from Ggit
     """
     revwalk = Git.RevisionWalker.new(repo)
-    revwalk.set_sort_mode(Git.SortMode.TIME)
     branch_ref = "refs/heads/%s" % branch
     revwalk.push_ref(branch_ref)