> > class mappingdict(mappable, _mappingsequence):
> > """Wrapper for a single template mapping
> >
> > This isn't a sequence in a way that the underlying dict won't be
> iterated
> > as a dict, but shares most of the _mappingsequence functions.
> > """
>
> > We might want to structure these variables as `base.node|short` instead of
> > `base_node` for example, but that would require more work.
[...]
> Unfortunately, this doesn't work super well, when using the following flags:
There isn't a building block for a mapping dict holding mapping
> +def _describemerge(ui, repo, env, toolpath, args):
> +template = ui.config('ui', 'pre-merge-tool-output-template')
> +if not template:
> +return
> +
> +# Remove HG_ prefix from entries in `env` and lowercase them
> +def sanitizeenv(k):
> +if k.startswith('HG_'):
