if gw_briefs set gw_trans->next_id in gw_summary, it was being carried over to gw_tags, causing the 'Next' link to be displayed.

This is a racy solution that needs to be properly implemented in the future. ok stsp

While merging a commit multiple times during a histedit operation could potentially make sense in some corner case, a commit appearing more than once in the script is more likely to happen accidentally. If desired, the same effect can still be achieved by running multiple histedit operations, or by using 'got cherrypick' while the histedit operation is paused for arbitrary editing.

Commit IDs on histedit's temporary branch can change arbitrarily because the user may create new commits on this branch while editing past commits. So there is no point in trying to verify these IDs like we do during rebase. Add a test case which demonstrates the problem.

Provide a useful error message in such cases and explicitly document intentional restrictions in the got(1) man page. Prompted by a question from Adam Steen via bsd.network https://bsd.network/@adams/103768951483318235