ApproveAndMergeAsync treated any non-Active worktree (including Kept, the
state RevertMergeAsync leaves behind) the same as "never had a worktree",
so re-approving a reverted task ran only the verify gate and marked the
task Done without merging anything back.
Now a Kept worktree is distinguished: if its branch is gone (the common
case, since approve normally deletes it), approve returns Blocked instead
of a fake "merged". If the branch survives, its tip is already an ancestor
of the target (from the original merge), so a plain `git merge` would
silently no-op ("Already up to date."); cherry-picking the original merge
commit's own diff (-m 1) is what actually restores the content, recorded
as a fresh MergeCommit.
Mika Kuns
8d597df448