Попробуйте следующее:
s = '111234'
l = re.findall(r'((.)\2*)', s)
## it this stage i have [('111', '1'), ('2', '2'), ('3', '3'), ('4', '4')] in l
## now I am keeping only the first value from the tuple of each list
lst = [x[0] for x in l]
print lst
вывод:
['111', '2', '3', '4']