Strategy in dealing with failed tests due to issues from other libraries

[haipinglu]

In #330 (comment) and #330 (comment), we encounterd the problem that errors in our testing are due to conflicts of other libraries, which may take some time to fix. Instead of waiting for the fix, what we prefer is to remove a miminal number of lines affected by such conflicts so that our tests can pass, sacrificing the coverage only slighly to be able to move forward.