Wrong work of the select elements with cyrillic names

Hi,
I have found that select elements with russian names (and any non-english letters) works wrong, when there are several elements that containing space in names.

Function _webform_safe_name strip all non-english letters and convert spaces to '_'. Then, if in list was two elements like 'русское слово' and 'другое слово', they will be equal: _. And second element will be hidden.

My patch checks if safe name contains only '_' symbols - then it will be encoded to base64 (like empty strings).