UnicodeDecodeError when setting tag units with unit of data array

Hi

Here is an example with nixio v1.3.0

import nixio as nix
import numpy as np

nixFile = nix.File.open('test.h5')
blk = nixFile.create_block('TestBlock', 'Test')
da = blk.create_data_array('TestDA', 'Test', data=np.random.rand(50))
da.unit = 'mV'
dim = da.append_sampled_dimension(1)
dim.unit = 's'

tag = blk.create_tag('TestTag', 'Test', position=[10])
tag.extent = [10]
tag.references.append(da)
tag.units = [da.dimensions[0].unit]
nixFile.close()

Here is the Traceback,

Traceback (most recent call last):
File "tmp/nixioUnicodeBug.py", line 14, in
tag.units = [da.dimensions[0].unit]
File "/home/aj/intel/intelpython27/envs/GJEMS/lib/python2.7/site-packages/nixio/pycore/tag.py", line 51, in units
u = util.units.sanitizer(u)
File "/home/aj/intel/intelpython27/envs/GJEMS/lib/python2.7/site-packages/nixio/pycore/util/units.py", line 66, in sanitizer
replace(micro, "u").replace(mugr, "u")
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc2 in position 0: ordinal not in range(128)

I could get around it with

tag.units = [str(da.dimensions[0].unit)]

Is this expected behavior? Thanks.