fix: bail if --chaos and specific version

See coop-cloud/organising#503.

tests/integration/app_rollback.bats

@@ -194,6 +194,13 @@ teardown(){
   _undeploy_app
 }
 
+@test "bail out if specific version and chaos" {
+  run $ABRA app rollback "$TEST_APP_DOMAIN" "0.2.0+1.21.0" \
+    --chaos --no-input --no-converge-checks
+  assert_failure
+  assert_output --partial 'cannot use'
+}
+
 # bats test_tags=slow
 @test "rollback to previous version" {
   run $ABRA app deploy "$TEST_APP_DOMAIN" "0.1.1+1.20.2" --no-input --no-converge-checks