The env var field in the default SICS start string should be blank.

By default SICS is launched with no environment variables and sudo
doesn't allow 'None' on the ICS computers.

site_ansto/instrument/runsics.py

@@ -61,7 +61,7 @@ def start_cmd(server, args):
     else:
         soffset = ''
     sicsenv = {
-        'none':       None,
+        'none':      '',
         'fullsim':   'SICS_SIMULATION=full%s' % soffset,
         'fakedev':   'SICS_SIMULATION=fakedev%s' % soffset,
         'scriptval': 'SICS_SIMULATION=script_validator%s' % soffset