the offending line is clients.py:1270

I use '<input name=":add:solves" size="20">' in my form
to add items to a 'solves' MultiLink attribute. However,
even if the field remains empty when I commit, the line

value = [i.strip() for i in value.value.split(',')]

will generate [''] from that, which, then, triggers the
error message 

'Error: new property "solves": not a bug'

(solves is a MultiLink attribute to entities of class
'bug')

I think a fix would be to remove all empty elements from
the 'value'. (which would make the code also more
robust for cases where users typed in something like
'12,13,' instead of '12,13'...)