Child loggers print duplicated bindings

[avaly]

I believe the change from #1367 has an undesired side effect to the output of the JSON fields in the log lines: the bindings are printed twice in child loggers.

Steps to reproduce

import pino from 'pino';

const log = pino();

log.info('Test info');
log.child({ category: 'CHILD' }).info('Test info');

Running this would print:

{"level":30,"time":1647938465297,"pid":43474,"hostname":"localhost","msg":"Test info"}
{"level":30,"time":1647938465297,"pid":43474,"hostname":"localhost","pid":43474,"hostname":"localhost","category":"CHILD","msg":"Test info"}

Notice the duplicated pid and hostname in the child log line.

[mcollina]

Good spot, I'll revert asap.

[github-actions]

This issue has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.