That's possible but what I've posted is all that is in my Notebook -- but not all that _was_ in the Notebook.
I re-checked from the ipython command line and it does work correctly.
Killing the tab and starting a new Notebook (flushing all variables) made it function correctly.
I can only assume that there was a typo in previous cells that were deleted.
A cell you've run stays run, even if you delete it. The "In :" in
your example means its the 26th bit of code you ran - and any of the
25 before it could have overwritten list.
Another thing to note is that all previously defined variables are persistent until the kernel is restarted. This may seem obvious but my initial tendency was to look at different cells as new instances.