Take the content of a list and append it to another list

You probably want

list2.extend(list1)

instead of

list2.append(list1)

Here’s the difference:

>>> a = [1, 2, 3]
>>> b = [4, 5, 6]
>>> c = [7, 8, 9]
>>> b.append(a)
>>> b
[4, 5, 6, [1, 2, 3]]
>>> c.extend(a)
>>> c
[7, 8, 9, 1, 2, 3]

Since list.extend() accepts an arbitrary iterable, you can also replace

for line in mylog:
    list1.append(line)

by

list1.extend(mylog)