Add mercurial to CVS

Heptapod is a friendly fork of GitLab and is being built by Octobus ❤

From the presentation at Mercurial Conference 2019 in Paris (https://slides.racinet.fr/2019/hg-paris/generated/#/step-5):

What is Heptapod ?

Heptapod = GitLab CE + Mercurial

• A friendly fork
• Excellent relationship with GitLab
• Featuring modern Mercurial workflows: evolve, topic

One should never have to force-push

There is no current plan to add Mercurial support to GitLab, but we are providing support to the Octobus team where needed as they work on Heptapod.

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Description

Can't host projects using mercurial. I find mercurial orders of magnitudes more friendly than git, for example I can remember the commands!

Proposal

Add mercurial as an option for the CVS

Links / references

https://confluence.atlassian.com/bitbucket/create-a-git-or-mercurial-repository-760120240.html