topics: improve the description if topic is not touched Instead of an empty stack in `hg stack` when topic does not contain any changeset, we show `not yet touched`.

topics: show working directory branch when topic is empty

topics: add tests for cases when a topic is empty

readme: mention compatibility with future 4.4

topic: update the message used with --age for empty topic This clarify things when a topic got emptied by publishing.

sharing: edit pass

user-guide: edit pass

topic: stabilise the output of --age when date ties We just needed to introduce sort to stabilize the output order.

tests: update after removing of redundant amend commit Following e8a7c1a0565a, temporary amend commits has been removed impacting all revision numbers in tests including amend operations. Update tests case to use description or hashes when possible and update revisions number when not.

topic: setup 'topic' value for working ctx The way amend work in core change in e8a7c1a0565a. The intermediate commit disappear and we can no longer rely on it to carry the topic value to amend. To fix this, we ensure the current topic value can be retrieved through the `workingctx.extra()` value. Since there is no way to carry a "missing" key information in a way that survives and "dict.update" call. We also has to introduce hacking behavior about a special empty value for topic.