The createsnapshot() of backup() will be executed repeatedly when err is nil

[zddr]

Steps to reproduce:
List the minimal actions needed to reproduce the behavior.

1. Analysis code Engine.Backup()

Expected behavior:
Jump out of the loop when err is nil

Actual behavior:
no break when err is nil

Environment info:

• System info: Run uname -srm and copy the output here
• InfluxDB version: Run influxd version and copy the output here
• Other relevant environment details: Container runtime, disk info, etc

Config:
Copy any non-default config values here or attach the full config as a gist or file.

Logs:
Include snippet of errors in log.

Performance:
Generate profiles with the following commands for bugs related to performance, locking, out of memory (OOM), etc.

# Commands should be run when the bug is actively happening.
# Note: This command will run for at least 30 seconds.
curl -o profiles.tar.gz "http://localhost:8086/debug/pprof/all?cpu=true"
curl -o vars.txt "http://localhost:8086/debug/vars"
iostat -xd 1 30 > iostat.txt
# Attach the `profiles.tar.gz`, `vars.txt`, and `iostat.txt` output files.

[lesam]

This was fixed by #20527 in master and #19869 in master-1.x