plan 8: generated apply and undo round trip; undo reverses chains within one file

1 files changed, 9 insertions, 0 deletions

diff --git a/internal/engine/apply.go b/internal/engine/apply.go
index 878cb18..ce05636 100644
--- a/internal/engine/apply.go
+++ b/internal/engine/apply.go
@@ -476,6 +476,15 @@ func planUndoFile(file string, ents []journal.Entry) UndoFile {
 			break
 		}
 		step := reverseStep(en)
+		if (en.Action == "move" || en.Action == "rename") && proj.occupied[en.Dst] {
+			// A reversal already queued for this same file puts it back at
+			// en.Dst before this one runs, and that reversal was checked
+			// against the disk itself. Judged against the disk as it is now,
+			// en.Dst is empty - a later step of the chain moved the file on -
+			// and every rename-then-move, move-then-move or move-then-trash
+			// chain would be refused (plan 8, found by the property test).
+			step.Refused = ""
+		}
 		if step.Refused == "" {
 			step.Refused = refuseIfSrcExists(step, proj)
 		}