Disable restic local caches

Local caches apparently require an exclusive lock, effectively
preventing concurrency -- it is still to be seen if the repository
lock has the same effect though.

repository_restic.go

@@ -154,7 +154,7 @@ func resticBackupTags(backup *Backup, ds *Dataset) string {
 
 func (r *resticRepository) BackupCmd(backup *Backup, ds *Dataset, sourcePaths []string) string {
 	return fmt.Sprintf(
-		"%s backup --cleanup-cache --exclude-caches --one-file-system %s %s",
+		"%s backup --no-cache --exclude-caches --one-file-system %s %s",
 		r.resticCmd(),
 		resticBackupTags(backup, ds),
 		strings.Join(sourcePaths, " "),
@@ -163,7 +163,7 @@ func (r *resticRepository) BackupCmd(backup *Backup, ds *Dataset, sourcePaths []
 
 func (r *resticRepository) getSnapshotID(ctx context.Context, rctx RuntimeContext, backup *Backup, ds *Dataset) (string, error) {
 	data, err := rctx.Shell().Output(ctx, fmt.Sprintf(
-		"%s snapshots --json %s",
+		"%s snapshots --no-cache --no-lock --json %s",
 		r.resticCmd(),
 		resticBackupTags(backup, ds),
 	))
@@ -209,7 +209,7 @@ func datasetStdinPath(ds *Dataset) string {
 func (r *resticRepository) BackupStreamCmd(backup *Backup, ds *Dataset) string {
 	fakePath := datasetStdinPath(ds)
 	return fmt.Sprintf(
-		"%s backup --cleanup-cache --exclude-caches %s --stdin --stdin-filename %s",
+		"%s backup --no-cache %s --stdin --stdin-filename %s",
 		r.resticCmd(),
 		resticBackupTags(backup, ds),
 		fakePath,