Will do, but to learn something: why is this necessary?

The branch behind this PR is based on an older version of the master branch, one which did not specify the proper minimum version requirements. Hence, trying to test minimum versions on this branch does current fail, see e.g. Travis.

In the meantime, the master branch has been updated and we now specify proper minimum version requirements (#113 and #115). However, we do not currently run any tests on the master branch for older versions (and it's debatable whether this is needed in the first place).

If you rebase this branch on the current master, then this branch will use the proper minimum version requirements.

If we were to accept this PR now without rebasing on master first, then we risk accepting a PR that does technically not build currently, but will will build once it's merged.

I hope this helps 👍