unbundle: use context manager for transaction

clonebundle: use context managers for lock and transaction

changeset_templater: render template specified by templatespec tuple

formatter: render template specified by templatespec tuple

formatter: put topic in templatespec tuple This will allow us to change the initial template reference depending on how the template is looked up. For example, -Tdefault => (ref='changeset', tmpl=None, mapfile='map-cmdline.default') -T'{rev}' => (ref='', tmpl='{rev}', mapfile=None) A literal template given by -T option will be stored as an unnamed template, which will free up the template namespace so that we can load named templates from [templates] section of user config.

cmdutil: pass templatespec tuple directly to changeset_templater (API) A fewer number of arguments should be better.

formatter: wrap (tmpl, mapfile) by named tuple I'm going to add more options to the templatespec tuple. cmdutil.logtemplatespec() is just an alias now, but it will be changed to a factory function later.

cmdutil: factor out helper to create changeset_templater with literal template changeset_templater has lots of arguments, but most callers only need to specify a literal template 'tmpl'. "hg debugtemplate" has no diff option, which means 'opts' were effectively {}, so dropped opts.