Reduction: error when attempting to re-map alias that points to read-only index

remap-readonly.sh

curl -XDELETE http://localhost:9200/test1?pretty=true
echo ''
curl -XDELETE http://localhost:9200/test2?pretty=true
echo ''
curl -XPUT http://localhost:9200/test1?pretty=true -d '{}'
echo ''
curl -XPOST http://localhost:9200/_aliases?pretty=true -d '{"actions":[{"add":{"index":"test1","alias":"test"}}]}'
echo ''
curl -XPUT http://localhost:9200/test2?pretty=true -d '{}'
echo ''
curl -XPUT http://localhost:9200/test1/_settings?pretty=true -d '{"index":{"blocks":{"read_only":true}}}'
echo ''
curl -XPOST http://localhost:9200/_aliases?pretty=true -d '{"actions":[{"remove":{"index":"test1","alias":"test"}},{"add":{"index":"test2","alias":"test"}}]}'
echo ''