backup/diff/dump/restore/stats: List snapshots before index

During a backup the index is written before the corresponding snapshots.
To ensure that a concurrent/later restic run can read a snapshot's data,
restic thus must first load the snapshots and only afterwards the index.
Otherwise it is not possible to ensure that the loaded index is recent
enough to cover all of the snapshot's data.

cmd/restic/cmd_dump.go

@@ -144,11 +144,6 @@ func runDump(opts DumpOptions, gopts GlobalOptions, args []string) error {
 		}
 	}
 
-	err = repo.LoadIndex(ctx)
-	if err != nil {
-		return err
-	}
-
 	var id restic.ID
 
 	if snapshotIDString == "latest" {
@@ -168,6 +163,11 @@ func runDump(opts DumpOptions, gopts GlobalOptions, args []string) error {
 		Exitf(2, "loading snapshot %q failed: %v", snapshotIDString, err)
 	}
 
+	err = repo.LoadIndex(ctx)
+	if err != nil {
+		return err
+	}
+
 	tree, err := repo.LoadTree(ctx, *sn.Tree)
 	if err != nil {
 		Exitf(2, "loading tree for snapshot %q failed: %v", snapshotIDString, err)