add VERSIONHACK markers for never-released plaintext handling

IPython/frontend/html/notebook/static/js/notebook.js

@@ -1197,7 +1197,8 b' var IPython = (function (IPython) {'
             var new_cell = null;
             for (i=0; i<ncells; i++) {
                 cell_data = new_cells[i];
-                // handle short-lived plaintext name for raw cells
+                // VERSIONHACK: plaintext -> raw
+                // handle never-released plaintext name for raw cells
                 if (cell_data.cell_type === 'plaintext'){
                     cell_data.cell_type = 'raw';
                 }

IPython/nbformat/v3/nbbase.py

@@ -114,7 +114,8 b' def new_code_cell(input=None, prompt_number=None, outputs=None,'
 def new_text_cell(cell_type, source=None, rendered=None):
     """Create a new text cell."""
     cell = NotebookNode()
-    # handle short-lived plaintext name for raw cells
+    # VERSIONHACK: plaintext -> raw
+    # handle never-released plaintext name for raw cells
     if cell_type == 'plaintext':
         cell_type = 'raw'
     if source is not None:

IPython/nbformat/v3/nbpy.py

@@ -68,6 +68,7 b' class PyReader(NotebookReader):'
                 state = u'markdowncell'
                 cell_lines = []
                 kwargs = {}
+            # VERSIONHACK: plaintext -> raw
             elif line.startswith(u'# <rawcell>') or line.startswith(u'# <plaintextcell>'):
                 cell = self.new_cell(state, cell_lines, **kwargs)
                 if cell is not None: