touch: extract the logic of touching rev's to its own function This refactoring will also help us in using the context manager for locks in next patches and also help reducing the nested depth.

changelog: mention user merging in the changelog

evolve: consider using three way merge to get the user for div resolution This patch adds the logic to merge the users from two divergent csets considering the base (i.e three way merge). The case when all the three are different, we concatenate the two authors of divergent csets.

evolve: add tests for the case when div csets has different users

branching: merge with stable

evolve: move status msg to verbose mode in content-divergence resolution As suggested by Pierre-Yves, lets move these too verbose message for the user to verbose mode to decrease some noise.

debian: Override default value for SPHINXBUILD in docs/makefile Sphinx now defaults to Python 3 in Debian Buster, so we need to explicitly select the Python 2 version of sphinx-build for building docs.

docs: add SPHINXBUILD make variable This defaults to sphinx-build. The current use case is for the Evolve Debian package build.

topic: add test to increase code coverage in case of multiple topics This patch adds a test which cover the part that when we have one topic on top of other topic, this make sure that when evolving it's boundary are the current active topic (i.e hg stack)

changelog: --no-update is the default, recommend --update instead