histedit: simplify computation of `newchildren` during --continue We are now checking for any changesets between the previous `parentctx` and the current working directory parent. If the current working directory parent is inconsistent, we abort. This change is useful as it simplifies the --continue process, easing upcoming changes. While working on this changeset, I spotted an unhandled corner case. This corner case is now documented and have an appropriate issue in the tracker (issue3655). However, the corner case is still unhandled. handling this test case would required some additional work: - actually decide what the proper behavior should be: - change content of "histedit-state" to add missing data necessary to detect the situation - add proper testcase, But leaving the case unhandled is "okay": - this is not a regression, - this is not the purpose of the current series, - the freeze was near and I had more critical stuff to attend to, - this is a simple but non trivial, (see above)