Unecessary error in --update-at-startup mode

[clefebvre]

To reproduce the issue:

• Open synaptic
• Block a package (this creates an entry in /var/lib/synaptic/preferences)
• Unblock the package (this leaves an empty line in /var/lib/synaptic/preferences)
• Refresh the cache ... everything works fine
• Close synaptic
• Run synaptic's refresh in update mode with:

sudo /usr/bin/synaptic --update-at-startup

and you get the following error:

Analysis:

The error comes from RAPTOptions::restore(), it is detected both in update mode and in normal mode. The difference between the two is that in update mode, the cache isn't opened prior to performing the refresh.

Proposed solution:

Initialize the cache also in update mode.

https://gitlab.com/linuxmint/pins/mint/synaptic/-/commit/7477fb52b03b95695110216fe61b30aa00524ae9

[clefebvre]

Downstream bug report: https://github.com/linuxmint/mintupdate/issues/627