Description of problem:
When non-root user use "systemctl",  it require the authentication.
But if user never input, the authentication become timeout as expected.
After the prompt comes back, user can not see the input of his/her.

Version-Release number of selected component (if applicable):
systemd-219-19.el7,  systemd-219-30.el7

How reproducible:
Always


Steps to Reproduce:
1. Login as non-root user.
2. Stop postfix service.
   When pam asked for authentication, never input and wait for timeout.
   $ systemctl stop postfix.service

==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ===
Authentication is required to manage system services or units.
Authenticating as: root
Password:   <=   Never input 

After timeout

Password: Failed to stop postfix.service: Connection timed out
polkit-agent-helper-1: pam_authenticate failed: Authentication failure

3. Shell prompt comes back.
   Then type something to the shell.

Actual results:
Can not see my input from the shell.

Expected results:
Can see my input from the shell.

Additional info:
Collect stty setting before and after the 
"$ systemctl stop postfix.service".

# diff stty-before.txt stty-after.txt
9c9
< isig icanon iexten echo echoe echok -echonl -noflsh -xcase -tostop -echoprt
---
> isig icanon iexten -echo -echoe -echok -echonl -noflsh -xcase -tostop -echoprt

echo, echoe, echok are disabled.

I type "stty echo" while no echo-back from shell,
then the shell re-start to echo back.