== bundle2 required ==
Old clients may see the following error when cloning from new servers:

{{{
$ hg clone https://example.com/repo  requesting all changes
abort: remote error:
incompatible Mercurial client; bundle2 required
(see https://www.mercurial-scm.org/wiki/IncompatibleClient)
[255]
}}}
This error means your client isn't using bundle2, which is a new wire protocol format added in Mercurial 3.5. To make the error go away, upgrade your Mercurial install to the latest stable release.