my snap cannot be build anymore - 'ascii' codec can't encode character

[Pawel Stolowski]

Hi,

I'm getting the following error when trying to 'snapcraft cleanbuild' 
something I contributed  a few weeks ago to playpen - 
https://github.com/ubuntu/snappy-playpen/tree/master/qcomicbook:

..... (installation of dependencies).....
Processing triggers for ureadahead (0.100.0-19) ...
'ascii' codec can't encode character '\u29f8' in position 19: ordinal 
not in range(128)
Command '['lxc', 'exec', 'snapcraft-hydrographically-foraminiferal-
magdalene', '--', 'snapcraft', 'snap', '--output',
'qcomicbook_0.9.1_amd64.snap']' returned non-zero exit status 1

it worked back then and I haven't touched it since... looks like a bug 
in snapcraft ?  Has anyone experienced it?

Cheers,
Pawel