Dialog executes primary action when the agent is called from terminal

[arshubham]

This only happens sometime. This happens when a app requests root from the terminal on launch.
Steps:

1. run snap refresh (more possibility of reproducing it when using tab completion)
2. Primary action is executed and Authentication failed message is shown.

Affects Juno beta 1

[kgrubb]

It looks like this happens when triggering polkit in other apps as well. For more information, take a look at the behavior we've found in switchboard-plug-locale: elementary/settings-locale#96