test: add support for random-all topic mode The 'random' mode no longer generate a random topic for merge.

test: rename test-topicmode to test-topic-mode This is easier to read.

topicmode: add 'random' topic mode That mode will generate a random topic name when the user is about to commit an untopiced changeset.

topic: update the topic-mode hint The hint is now shorter and reference the documentation. That should provide more concise output with more details for user who seeks it.

topic: rename the 'topic-mode' help subtopic This will help making reference to it in warning.

topic: add a 'enforce-all' mode The mode abort for all commit without a topic, even merges.

topicmode: 'enforce' topic mode, no longer warn about untopiced merge merging a topic back in a branch is common case, it seems sensible to not pester the user about it.

topicmode: add new warning topicmode

topic: add documentation for the 'topic-mode' option This should help people to discover it.

test: update tests to use topic-mode enforce

topic: migrate experimental.enforce-topic to experimental.topic-mode

test: adapt to output change from 10e162bb9bf5 The changeset 10e162bb9bf5 in code extend the list of capabilities to include "phases=['heads']" this has a minor impact on test output CORE-TEST-OUTPUT-UPDATE: 10e162bb9bf5

merge with stable

stack: handle basic case of splitting with crash hg stack used to crash horribly whenever a split was encountered. This is no longer the case. If the result of the split (or there successors) produce a sensible linear result with on final head, we can just assume that head is the evolution destination.