Non-f-of-t Nodes break when fed into passthrough Nones

[tcstewar]

Here's a minimal example:

import nengo
import nengo_spinnaker
import numpy as np

model = nengo.Network()
with model:
    def stim_func(t):
        return np.sin(t), np.cos(t)
    stim = nengo.Node(stim_func)

    ea = nengo.networks.EnsembleArray(n_neurons=50, n_ensembles=2)
    nengo.Connection(stim, ea.input)

sim = nengo_spinnaker.Simulator(model)
sim.run(1)

and here's the error:

Building finished in 0:00:01.
Traceback (most recent call last):
  File "input_func_test.py", line 15, in <module>
    sim.run(1)
  File "/localhome/tcstewar/github/nengo_spinnaker/nengo_spinnaker/simulator.py", line 244, in run
    self.run_steps(steps)
  File "/localhome/tcstewar/github/nengo_spinnaker/nengo_spinnaker/simulator.py", line 250, in run_steps
    self._run_steps(n_steps)
  File "/localhome/tcstewar/github/nengo_spinnaker/nengo_spinnaker/simulator.py", line 300, in _run_steps
    self.host_sim.step()
  File "/localhome/tcstewar/github/nengo/nengo/simulator.py", line 308, in step
    step_fn()
  File "/localhome/tcstewar/github/nengo/nengo/builder/operator.py", line 626, in step_simpyfunc
    y = fn(t.item(), *args) if t is not None else fn(*args)
  File "/localhome/tcstewar/github/nengo_spinnaker/nengo_spinnaker/simulator.py", line 377, in func
    return f(t, x)
  File "/localhome/tcstewar/github/nengo_spinnaker/nengo_spinnaker/builder/node.py", line 340, in output
    self.controller.set_node_output(self.target, value)
  File "/localhome/tcstewar/github/nengo_spinnaker/nengo_spinnaker/node_io/ethernet.py", line 126, in set_node_output
    c_value = np.dot(transform, c_value)
ValueError: shapes (1,1) and (2,) not aligned: 1 (dim 1) != 2 (dim 0)

This doesn't happen if the input goes straight to an Ensemble, or if the input is marked as function_of_time=True.