You can potentially close an EventSource before its first tick by
immediately setting the readyState to a non-open state. Therefore it
never opens.
Calling `open` will then open it.
'Open' fits better than 'reopen' when taking the above into account
- Maintain http headers as JSON-API meta for all API requests (#4946)
- Add EventSource ready for implementing blocking queries
- EventSource project implementation to enable blocking queries for service and node listings (#5267)
- Add setting to enable/disable blocking queries (#5352)