Support adding parents to a commit.

pygit2.c

@@ -668,6 +668,39 @@ Commit_get_parents(Commit *commit)
     return list;
 }
 
+static PyObject *
+Commit_add_parent(Commit *self, PyObject *parent)
+{
+    int err;
+    git_commit *parent_commit;
+
+    if (PyString_Check(parent)) {
+        git_oid oid;
+
+        err = py_str_to_git_oid(parent, &oid);
+        if (err < 0)
+            return Error_set_py_obj(err, parent);
+
+        err = git_commit_lookup(&parent_commit, self->repo->repo, &oid);
+        if (err < 0)
+            return Error_set_py_obj(err, parent);
+    } else {
+        if (!PyObject_TypeCheck(parent, &CommitType)) {
+            PyErr_Format(PyExc_TypeError, "target must be %.200s, not %.200s",
+                         CommitType.tp_name, parent->ob_type->tp_name);
+            return NULL;
+        }
+
+        parent_commit = ((Commit *) parent)->commit;
+    }
+
+    err = git_commit_add_parent(self->commit, parent_commit);
+    if (err < 0)
+        return Error_set(err);
+
+    Py_RETURN_NONE;
+}
+
 static PyGetSetDef Commit_getseters[] = {
     {"message_short", (getter)Commit_get_message_short, NULL, "short message",
      NULL},
@@ -684,6 +717,12 @@ static PyGetSetDef Commit_getseters[] = {
     {NULL}
 };
 
+static PyMethodDef Commit_methods[] = {
+    {"add_parent", (PyCFunction)Commit_add_parent, METH_O,
+     "Add a new parent commit to an existing commit."},
+    {NULL}
+};
+
 static PyTypeObject CommitType = {
     PyObject_HEAD_INIT(NULL)
     0,                                         /*ob_size*/
@@ -713,7 +752,7 @@ static PyTypeObject CommitType = {
     0,                                         /* tp_weaklistoffset */
     0,                                         /* tp_iter */
     0,                                         /* tp_iternext */
-    0,                                         /* tp_methods */
+    Commit_methods,                            /* tp_methods */
     0,                                         /* tp_members */
     Commit_getseters,                          /* tp_getset */
     0,                                         /* tp_base */

test/test_commit.py

@@ -67,6 +67,10 @@ class CommitTest(utils.BareRepoTestCase):
         commit.committer = committer
         commit.author = author
 
+        self.assertEqual(0, len(commit.parents))
+
+        commit.add_parent(COMMIT_SHA)
+
         self.assertEqual(None, commit.sha)
         self.assertEqual(pygit2.GIT_OBJ_COMMIT, commit.type)
         self.assertEqual(message, commit.message)
@@ -74,6 +78,8 @@ class CommitTest(utils.BareRepoTestCase):
         self.assertEqual(12346, commit.commit_time)
         self.assertEqual(committer, commit.committer)
         self.assertEqual(author, commit.author)
+        self.assertEqual(1, len(commit.parents))
+        self.assertEqual(COMMIT_SHA, commit.parents[0].sha)
 
     def test_modify_commit(self):
         message = 'New commit.\n\nMessage.\n'