IN the bottom the errors. There two related to nest3, one about the 'install' module and the other about the attribute 'kernel'
Thanks for the hints.
In [1]: import pyNN as p
In [2]: p.__version__
Out[2]: '
0.10.0.dev'
In [3]: import pyNN.nest as sim
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
~/PyNN/pyNN/nest/simulator.py in __init__(self)
     56         try:
---> 57             nest.Install('pynn_extensions')
     58             self.extensions_loaded = True
AttributeError: module 'nest' has no attribute 'Install'
During handling of the above exception, another exception occurred:
AttributeError                            Traceback (most recent call last)
<ipython-input-3-3a2fb0d916c8> in <module>
----> 1 import pyNN.nest as sim
~/PyNN/pyNN/nest/__init__.py in <module>
     16 import nest
     17 
---> 18 from . import simulator
     19 from pyNN import common, recording, errors, space, __doc__
     20 from pyNN.common.control import DEFAULT_MAX_DELAY, DEFAULT_TIMESTEP, DEFAULT_MIN_DELAY
~/PyNN/pyNN/nest/simulator.py in <module>
    267 # --- Initialization, and module attributes ------------------------------------
    268 
--> 269 state = _State()  # a Singleton, so only a single instance ever exists
    270 del _State
~/PyNN/pyNN/nest/simulator.py in __init__(self)
     57             nest.Install('pynn_extensions')
     58             self.extensions_loaded = True
---> 59         except nest.kernel.NESTError as err:
     60             self.extensions_loaded = False
     61         self.initialized = False
AttributeError: module 'nest' has no attribute 'kernel'