Description of problem:
Running 'systemctl isolate' on any target disconnects any active sessions, including sending signal 15 to ssh sessions from other users.

Version-Release number of selected component (if applicable):

In RHEL 7.6 + RHEL 7.7
systemd.x86_64 0:219-67.el7_7.1
systemd-sysv.x86_64 0:219-67.el7_7.1           
systemd-libs.x86_64 0:219-67.el7_7.1
libgudev1.x86_64 0:219-67.el7_7.1

In RHEL 7.7 you must also downgrade:
systemd-python.x86_64 0:219-67.el7_7.1

How reproducible:

Consistently

Steps to Reproduce:

In a fresh RHEL 7.6 VM: 
1) run # yum update
2) create test accounts.
3) login to all sessions and a root session via ssh in multiple terminals
4) In the root terminal run # systemctl isolate multi-user.target 
5) Watch everyone get disconnected.

Actual results:

Test session 1:

$ ssh test1.122.4
test1.122.4's password: 

After issuing isolate on root session:

[test1@localhost ~]$ Connection to 192.168.122.4 closed by remote host.
Connection to 192.168.122.4 closed.

Test session 2:

$ ssh test2.122.4
test2.122.4's password: 

After issuing isolate on root session:

[test2@localhost ~]$ Connection to 192.168.122.4 closed by remote host.
Connection to 192.168.122.4 closed.

Root Session:

$ ssh root.122.4
root.122.4's password: 
Last login: Fri Aug 23 16:52:31 2019 from gateway

[root@localhost ~]# systemctl isolate multi-user.target
Connection to 192.168.122.4 closed by remote host.
Connection to 192.168.122.4 closed.

Expected results:

[root@localhost ~]# systemctl isolate multi-user.target
[root@localhost ~]# 

(no session disconnects)

Additional info:

Running the following to downgrade packages resolves the issue as a workaround:

RHEL 7.6:
# yum downgrade systemd systemd-sysv systemd-libs libgudev1

RHEL 7.7:
# yum downgrade systemd systemd-sysv systemd-libs libgudev1 systemd-python