Field.from_random crashes mpi

Hi,

I found another bug with mpi:

minimal_example.py

the error I get is:

[MainThread][ERROR   ] root         Uncaught exception
Traceback (most recent call last):
  File "minimal_example-3.py", line 16, in <module>
    std=some_diagonal.val)
  File "/usr/local/lib/python2.7/dist-packages/ift_nifty-3.1.0-py2.7.egg/nifty/field.py", line 251, in from_random
    lambda shape: generator_function(dtype=f.dtype,
  File "/usr/local/lib/python2.7/dist-packages/d2o/distributed_data_object.py", line 469, in apply_generator
    self.set_local_data(generator(self.distributor.local_shape), copy=copy)
  File "/usr/local/lib/python2.7/dist-packages/ift_nifty-3.1.0-py2.7.egg/nifty/field.py", line 253, in <lambda>
    **random_arguments))
  File "/usr/local/lib/python2.7/dist-packages/ift_nifty-3.1.0-py2.7.egg/nifty/random.py", line 50, in normal
    x *= dtype.type(std)
ValueError: operands could not be broadcast together with shapes (16,64,64) (64,64,64) (16,64,64) 
-------------------------------------------------------
Primary job  terminated normally, but 1 process returned
a non-zero exit code.. Per user-direction, the job has been aborted.
-------------------------------------------------------
--------------------------------------------------------------------------
mpirun detected that one or more processes exited with non-zero status, thus causing
the job to be terminated. The first process to do so was:

  Process name: [[29272,1],1]
  Exit code:    1
--------------------------------------------------------------------------

I only get it if the std in from_random is a array, for numbers it seems to work

Jakob