Apply database migration on backup restore

Backups restored to a newer version of SecureDrop may introduce breakage
if a migration has occurred. dpkg-reconfigure will call the postinst
which will in turn apply all necessary alembic migrations to the
database.

install_files/ansible-base/roles/restore/files/restore.py

@@ -45,7 +45,8 @@ def main():
     # If the process exits with a non-zero return code, raises an exception.
     subprocess.check_call(['service', 'apache2', 'restart'])
     subprocess.check_call(['service', 'tor', 'reload'])
-
+    # Apply database migrations (if backed-up version < version to restore)
+    subprocess.check_call(['dpkg-reconfigure', 'securedrop-app-code'])
 
 if __name__ == "__main__":
     main()