Fix issue340

[reikdas]

Fixes #340
My understanding of the fLast attribute of the TKey of TBaskets was wrong.
Added some more tests.

[jpivarski]

Let me know when you think this is done and want it to be merged. Thanks!

[reikdas]

It is done and can be merged once all the tests pass :)

[jpivarski]

Great! I'll do that (once the tests pass) and you can tell Matthieu that it's fixed, if you haven't already. (Has the version number been bumped? If so, I'll make a new release as well.)

[reikdas]

and you can tell Matthieu that it's fixed, if you haven't already.

I'll comment on the issue once this PR has been merged.

(Has the version number been bumped? If so, I'll make a new release as well.)

Yes :)
(Note - I made another PR today where I did not bump the version number, so if that get merged there could be just one release with both the changes?)

[jpivarski]

I didn't realize there was another PR. Maybe it would be easier if you merge both, draft a release, and then point me to the draft?

[reikdas]

I have drafted a release (https://github.com/scikit-hep/uproot/releases) but perhaps we should wait till I add the fix for append? It is trivial and I should get it done very soon.

[jpivarski]

Sure, I'll wait. Just let me know when.