Create a new branch at a certain revision

Question

Preface: Mercurial branches are two types:

Named Branch

In order to get named branch BRANCHNAME, starting at REV

hg update REV
hg branch BRANCHNAME
...
hg commit

commit is a must, because

the branch will not exist in the repository until the next commit

as noted in hg help branch

hg update REV
...
hg commit

and current branch get additional head

And as a last step, use the following command to create a remote branch and push the changesets.

hg push --new-branch