LogRecord "extra" data leaking between handlers

[Cosmin Ardeleanu]

Monolog version: latest released v3.

---

Context:

• Let's say i have 3 handlers attached to monolog logger: file handler, slack handler, elastic search handler.
  • Note that each handler can push its own processor, which can alter the LogRecord entity.
• On the elastic search handler, we need extra info, so push a processor to add them, (stupid example: $logRecord->extra['new_entry_just_for_elastic_search'] = 'stuff';
  • This "extra" data i also available for file handler and slack handler.
  • Basically i will get in slack handler and file handler, this extra that was supposed to be only for elastic search handler.

Why this is happening?

• LogRecord is passed by reference, to each handler.
• LogRecord accepts to alter data from extra, so if one handlers manages to alter this object, rest of remaining handlers, will use the altered object.

Created PR to fix this -> #1819

[Cosmin Ardeleanu]

@Seldaek ^^