I am experiencing a strange issue.  My configuration details are as follows:

OS: ubuntu 16.04

Jenkins version: 2.150

I am automating the deployment of Jenkins and pwauth plugin using Ansible.  As part part of my debugging I disabled the security by setting useSecurity to false.

root@mi-jenkins:/home/vagrant# nano /var/lib/jenkins/config.xml
root@mi-jenkins:/home/vagrant# ls -l /var/lib/jenkins/config.xml
rw-rr- 1 jenkins jenkins 6414 Nov 14 12:07 /var/lib/jenkins/config.xml
root@mi-jenkins:/home/vagrant# head /var/lib/jenkins/config.xml
<?xml version='1.1' encoding='UTF-8'?>
<hudson>
<disabledAdministrativeMonitors>
<string>jenkins.diagnostics.RootUrlNotSetMonitor</string>
</disabledAdministrativeMonitors>
<version>2.150</version>
<installStateName>RUNNING</installStateName>
<numExecutors>2</numExecutors>
<mode>NORMAL</mode>
<useSecurity>false</useSecurity>

I then go to the jenkins url and issue a post request of reload, https://<jenkins-url>/reload and the security is disabled however the config.xml file has changed on the server.

root@mi-jenkins:/home/vagrant# ls -l /var/lib/jenkins/config.xml
rw-rr- 1 jenkins jenkins 6412 Nov 14 12:09 /var/lib/jenkins/config.xml
root@mi-jenkins:/home/vagrant# head /var/lib/jenkins/config.xml
<?xml version='1.1' encoding='UTF-8'?>
<hudson>
<disabledAdministrativeMonitors>
<string>jenkins.diagnostics.RootUrlNotSetMonitor</string>
</disabledAdministrativeMonitors>
<version>2.150</version>
<installStateName>RUNNING</installStateName>
<numExecutors>2</numExecutors>
<mode>NORMAL</mode>
<useSecurity>true</useSecurity>

The irony is that while useSecurity is set to true even after restarting jenkins few times and reloading jenkins I don't see any login screen. I hope this is the correct place to report this bug.