merge with stable

histedit: delete all non-actionclass related code Now that all actions have been migrated to the class format, we can delete all the unnecessary code that supported the old function format.

histedit: improve roll action integration with fold Previously the fold action would inspect it's class to figure out if it was a rollup or not. This was hacky. Now that finishfold is inside the fold class, let's modify it to check a function (which roll can override) to determine if it should be prompting for a commit message.

histedit: move finishfold into fold class Let's move the finishfold function into the fold class so we can modify it from the roll class more easily.

histedit: convert fold/roll actions into a class This converts the fold/roll actions into a histeditclass instance, as part of an ongoing effort to refactor histedit for maintainability and robustness. The tests changed for two reasons: 1) We get a new 'empty changeset' warning because we now warn more consistently between normal histedit and --continue about commits disappearing. 2) Previously we were not putting the histedit-source extra field on the temporary fold commit during normal runs, but we were on --continue runs. By unifying these code paths we now consistently put histedit-source on the temporary fold commit, which changes some of the hashes in the backup bundles.

histedit: convert edit action into a class This converts the edit action into a histeditclass instance, as part of an ongoing effort to refactor histedit for maintainability and robustness.

histedit: convert message action into a class This converts the message action into a histeditclass instance, as part of an ongoing effort to refactor histedit for maintainability and robustness.

histedit: convert drop action into a class This converts the drop action into a histeditclass instance, as part of an ongoing effort to refactor histedit for maintainability and robustness.

histedit: convert pick action into a class This converts the pick action into a histeditclass instance, as part of an ongoing effort to refactor histedit for maintainability and robustness. The test output changed because previously pick would only report the commit disappearing if there were no merge conflicts. Now that we've unified the normal and the --continue flows, they act the same and we get the warning even after --continue.

histedit: integrate action class into flow This takes the newly added histeditaction class and integrates it into the histedit run and bootstrapcontinue logic. No actions implement the class yet, but they will be add in upcoming patches.