Misleading log message in distributed mode

[parberge]

Describe the bug

When running locust in distributed mode you can still get this warning message on the master node:

/WARNING/locust.main: System open file limit setting is not high enough for load testing, and the OS didn't allow locust to increase it by itself. See https://github.com/locustio/locust/wiki/Installation#increasing-maximum-number-of-open-files-limit for more info.

Since the master won't execute any of the tests this warning is misleading.

Expected behavior

No log message about open file limit on master when running distributed

Actual behavior

Log message about low open file limit on instance running master mode

Steps to reproduce

Run locust --master on a host with low open file limit (e.g 2048).

Environment

• OS: locust docker image running on Linux host
• Python version: Embedded version in docker image with tag 1.2.3
• Locust version: 1.2.3
• Locust command line that you ran: locust --master
• Locust file contents (anonymized if necessary): N/A