[borg] enable BORG_UNKNOWN_UNENCRYPTED_REPO_ACCESS_IS_OK

Otherwise the handler may hang, waiting for user input. This may occur
when the borg cache is deleted, or when borg is upgraded.

handlers/borg.in

@@ -15,6 +15,7 @@
 #
 
 export BORG_RELOCATED_REPO_ACCESS_IS_OK=yes
+export BORG_UNKNOWN_UNENCRYPTED_REPO_ACCESS_IS_OK=yes
 
 ### GET CONFIG ###