pcolormesh supports a keyword argument edgecolors. This can be of type str. Currently, it makes a difference whether i say pcolormesh(edgecolors='none') and pcolormesh(edgecolors='None'). This is very un-intuitive, especially since None means something different then "None".
I would like the behaviour to be the same whether edgecolors is "None", "NONE", "none", or whatever.
I don't remember when, but this was fixed; I can't reproduce the problem now.