PyASN1 0.6.1 broke compatibility

[number492]

PyASN1 made a new release [1] with a lot of Python 2 code removed, including compat/octets.py [2]. This is used by robotframework-snmplibrary [3], and now certain functionality is broken. There might be other issues too.

1: https://github.com/pyasn1/pyasn1/releases/tag/v0.6.1
2: pyasn1/pyasn1@6f770ba
3:

robotframework-snmplibrary/src/SnmpLibrary/library.py

Line 18 in 23a019f

from pyasn1.compat.octets import null