sorted list of exec nodes?

[alexsavio]

Hi,

Why do you use sorted in this line?
https://github.com/nipy/nipype/blob/master/nipype%2Fpipeline%2Fengine%2Fworkflows.py#L693

If I use a connect with an auxiliary function, e.g.:
(params, stc, [(("slice_order", sum_one), "slice_order"),]),

I get this error:
TypeError('unorderable types: tuple() < str()',)

Can't sort tuples against strings.

I removed the sorted because it doesn't make sense here and it works.

[satra]

@alexsavio - this looks like a bug. in fact would be good to add this as a test and fix it.