fixed Commit.stats retrieval for parentless commits in bare repos

(cherry picked from commit 88852ed7bcde4f4b18c1ae8b6fba7f3fab8e9bf5)

Author: empty

CHANGES

@@ -24,6 +24,9 @@ Commit
   the first line) and a new property ``Commit.summary`` contains the first
   line of the commit message.
 
+* Fixed a failure when trying to lookup the stats of a parentless commit from
+  a bare repo.
+
 Diff
 ----
 * The diff parser is now far faster and also addresses a bug where

lib/git/commit.py

@@ -165,7 +165,7 @@ def list_from_string(cls, repo, text):
 
             message = '\n'.join(messages)
 
-            commits.append(Commit(repo, id=id, parents=parents, tree=tree, author=author, authored_date=authored_date, 
+            commits.append(Commit(repo, id=id, parents=parents, tree=tree, author=author, authored_date=authored_date,
                                   committer=committer, committed_date=committed_date, message=message))
 
         return commits
@@ -224,11 +224,11 @@ def diffs(self):
     @property
     def stats(self):
         if not self.parents:
-            text = self.repo.git.diff(self.id, '--', numstat=True)
+            text = self.repo.git.diff_tree(self.id, '--', numstat=True, root=True)
             text2 = ""
-            for line in text.splitlines():
+            for line in text.splitlines()[1:]:
                 (insertions, deletions, filename) = line.split("\t")
-                text2 += "%s\t%s\t%s\n" % (deletions, insertions, filename)
+                text2 += "%s\t%s\t%s\n" % (insertions, deletions, filename)
             text = text2
         else:
             text = self.repo.git.diff(self.parents[0].id, self.id, '--', numstat=True)

test/fixtures/diff_tree_numstat_root

@@ -0,0 +1,3 @@
+634396b2f541a9f2d58b00be1a07f0c358b999b3
+18	29	a.txt
+5	0	b.txt

test/git/test_commit.py

@@ -129,7 +129,7 @@ def test_diffs(self, git):
         assert_equal(True, diffs[5].new_file)
 
         assert_true(git.called)
-        assert_equal(git.call_args, (('diff', '-M', 
+        assert_equal(git.call_args, (('diff', '-M',
                                               '038af8c329ef7c1bae4568b98bd5c58510465493',
                                               '91169e1f5fa4de2eaea3f176461f5dc784796769',
                                       ), {'full_index': True}))
@@ -190,7 +190,7 @@ def test_diffs_with_mode_only_change(self, git):
 
     @patch_object(Git, '_call_process')
     def test_stats(self, git):
-        git.return_value = fixture('diff_numstat')
+        git.return_value = fixture('diff_tree_numstat_root')
 
         commit = Commit(self.repo, id='634396b2f541a9f2d58b00be1a07f0c358b999b3')
         commit.__bake_it__()
@@ -201,7 +201,7 @@ def test_stats(self, git):
         assert_equal(["a.txt", "b.txt"], keys)
 
         assert_true(git.called)
-        assert_equal(git.call_args, (('diff', '634396b2f541a9f2d58b00be1a07f0c358b999b3', '--'), {'numstat': True}))
+        assert_equal(git.call_args, (('diff_tree', '634396b2f541a9f2d58b00be1a07f0c358b999b3', '--'), {'numstat': True, 'root': True }))
 
     @patch_object(Git, '_call_process')
     def test_rev_list_bisect_all(self, git):