text_error_template doesn't work with Python 3K #137

Migrated issue, originally created by Anonymous

The template source within text_error_template in exceptions.py contains "unicode.strip" which of course Python 3K doesn't understand :

% for (filename, lineno, function, line) in tback.traceback:
File "${filename}", line ${lineno}, in ${function or '?'}
${line | unicode.strip}
% endfor