transaction: rename find to findoffset and drop backup file support transaction.find used to support access to both the regular file and backup file list. They have different formats, so any consumer has to be aware of the difference alredy. There is no in-core consumer for the backup file access, so don't provide it. Differential Revision: https://phab.mercurial-scm.org/D9276

transaction: drop per-file extra data support At the moment, transactions support an optional extra data argument for all files to be stored in addition to the original offset. This is used in core only by the revlog inline to external data migration. It is used to memoize the number of revisions before the transaction. That number of can be computed during the walk easily, so drop the requirement. Differential Revision: https://phab.mercurial-scm.org/D9275

templates: define a {onelinesummary} keyword It is sometimes useful to be able to use the configured `command-template.oneline-summary` in higher-level templates. For example, I would like to use it in an internal template that lists commits in a "review unit" (kind of a pull request). This patch adds support for that. We may want to define a way of formatting a context using a command-specific override (from `command-templates.oneline-summary.<command>`), but that will have to be a template function instead. I don't plan to do that, but I'm mentioning it now in case reviewers would prefer that we use a no-arg function (i.e. `{onelinesummary()}`) already today to prepare for that. Differential Revision: https://phab.mercurial-scm.org/D9314