Você precisa editar este arquivo /usr/lib/python2.7/idlelib/IOBinding.py:
def coding_spec(str):
"""Return the encoding declaration according to PEP 263.
Raise LookupError if the encoding is declared but unknown.
"""
# Only consider the first two lines
str = str.split("\n", 2)[:2]
for line in lst:
Substitua str por lst:
def coding_spec(str):
"""Return the encoding declaration according to PEP 263.
Raise LookupError if the encoding is declared but unknown.
"""
# Only consider the first two lines
lst = str.split("\n", 2)[:2]
for line in lst:
Eu tive o mesmo problema e isso funcionou para mim.