juliantaylor/ipython — comment on commit e68660659803dfc67b3d05e89f8b3013f6a11cae
File: IPython/frontend/terminal/interactiveshell.py line 241
By takluyver:

Note that this would store the history length before we run the cell. If the user does `raw_input()` inside the cell, that will add an extra entry in readline history, which will make a mess of joining that cell back up.