What would you like to be added?

This is limitation of https://github.com/etcd-io/gofail library we use in linearizability and functional testing. In command line interface user can provide multiple failpoints, but when using HTTP endpoint we can only provide one failpoint at once https://github.com/etcd-io/gofail#http-endpoint.

Why is this needed?

This would allow better reproduction of more complicated issues. Some reproduction requires coordinating multiple independent processes within etcd. For example we could inject sleep in one routine and panic in other.