Install failure: "Recurse failed: none of the specified sources were found"

[eloquence]

This was originally noticed once in QA but resolved after dom0 updates, and has now been noticed once in a production install. During securedrop-admin --apply, the following error may occur:

          ID: dom0-securedrop-launcher-directory
    Function: file.recurse
        Name: /opt/securedrop/launcher
      Result: False
     Comment: Recurse failed: none of the specified sources were found
     Started: 20:52:46.766870
    Duration: 2.371 ms
     Changes:   

[eloquence]

qubesctl provides a saltutil.sync_all command, the documentation for which states:

Sync all modules. If a problem exists, one may remove the salt cache directory (rm -r /var/cache/salt) and re-sync the modules

In a production install, removing the salt cache directory resolved the issue above. @emkll, could you document which commands you ran to resolve, i.e. did you just remove the cache directory, or also run the sync command?

[eloquence]

Mickael clarified that syncing alone did not resolve, but cleaning cache & syncing did. To attempt to resolve the issue, we've agreed to add these steps (clear cache & sync) to securedrop-admin --apply. I'll take a stab at this so we can test it.

[eloquence]

We've not observed this since #530 was merged, so closing for now.