fix for own error in edge-rotate keeping edge customdata - this was crashing when rotating multiple edges.

Now create the rotate edge in advance and copy its customdata (before joining the faces).

This commit also fixes an annoyance where tryangulating faces could create duplicate edges.

source/blender/python/bmesh/bmesh_py_utils.c

@@ -363,7 +363,7 @@ static PyObject *bpy_bm_utils_face_split(PyObject *UNUSED(self), PyObject *args)
 
 	f_new = BM_face_split(bm, py_face->f,
 	                      py_vert_a->v, py_vert_b->v,
-	                      &l_new, py_edge_example ? py_edge_example->e : NULL);
+	                      &l_new, py_edge_example ? py_edge_example->e : NULL, FALSE); /* BMESH_TODO, make arg */
 
 	if (f_new && l_new) {
 		PyObject *ret = PyTuple_New(2);
@@ -406,7 +406,7 @@ static PyObject *bpy_bm_utils_face_join(PyObject *UNUSED(self), PyObject *value)
 
 	/* Go ahead and join the face!
 	 * --------------------------- */
-	f_new = BM_faces_join(bm, face_array, (int)face_seq_len, TRUE); /* BMESH_TODO, make optional */
+	f_new = BM_faces_join(bm, face_array, (int)face_seq_len);
 
 	if (f_new) {
 		return BPy_BMFace_CreatePyObject(bm, f_new);