Mythril - Fix tests and build

Mythril is a security analysis tool for Ethereum smart contracts, written in Python.

There is a problem with Mythril unit tests (https://github.com/ConsenSys/mythril/issues/118) that causes failures of its Circle CI builds (https://github.com/ConsenSys/mythril/issues/116). In this challenge you are expected to fix the problems discussed in both issue tickets.

Final Submission Guidelines

Submit Git patch against the latest commit in master branch of Mythril repo (d0a3858400b727bdc5c927487e0dcc69ca1ef14d at the moment of writing). Also include a brief note on how you fixed the issue, what was the reason, and how it should be verified (especially, if you find out the issue/fix to be somewhat different from what is written in the issue discussions).