The python code mentioned is still susceptible to timing attacks. Not on the same scale as a bytewise, return on first inequality algorithms, but it's there. The return statement will take longer when the result value is 0, because then it will compare 2 lengths of strings. This could be enough to distinguish between correct and incorrect compares.

Since the usage of zip in that case will only compare the shorter of the strings to the start of the longer string, you can still achieve the timing attack, since the only inconsistency happens on the final comparison.

A better solution would be to check for length equality before doing the zip, or to pad the shorter of the strings compared to the length of the longer. Maybe also to just make the return statement:

return (len(a) == len(b)) and (result == 0)

which may be sufficient.