Dear Maintainer,

When trying to run synaptic-pkexec, the authentication doesn't work; met
with the following error:

```
** (process:4867): WARNING **: 19:38:27.478: Unknown line 'polkit-agent-helper-1: error response to PolicyKit daemon: GDBus.Error:org.freedesktop.PolicyKit1.Error.Failed: No session for cookie' from helper
==== AUTHENTICATION FAILED ====
Error executing command as another user: Not authorized

This incident has been reported.
```

I found this issue on github:
https://github.com/polkit-org/polkit/issues/686, so it is known to the
upstream developers, and I am reporting it to let know that it does
affect the current version in debian testing. Downgrading from 127-3 to
126-2 did fix it.