Only forget old backups if the directory already exists

src/freedombone

@@ -2469,8 +2469,10 @@ function backup_directory_to_usb {
       echo -n "}' | awk -F '/' '{print " >> /usr/bin/$BACKUP_SCRIPT_NAME
       echo -n '$2' >> /usr/bin/$BACKUP_SCRIPT_NAME
       echo "}')" >> /usr/bin/$BACKUP_SCRIPT_NAME
-      echo -n "    obnam forget --keep=${BACKUP_MAX_DAYS}d " >> /usr/bin/$BACKUP_SCRIPT_NAME
-	  echo '-r $USB_MOUNT/backup/${2} --encrypt-with $MY_BACKUP_KEY_ID ${1}' >> /usr/bin/$BACKUP_SCRIPT_NAME
+      echo '    if [ -d $USB_MOUNT/backup/${2} ]; then' >> /usr/bin/$BACKUP_SCRIPT_NAME
+      echo -n "      obnam forget --keep=${BACKUP_MAX_DAYS}d " >> /usr/bin/$BACKUP_SCRIPT_NAME
+      echo '-r $USB_MOUNT/backup/${2} --encrypt-with $MY_BACKUP_KEY_ID ${1}' >> /usr/bin/$BACKUP_SCRIPT_NAME
+      echo '    fi' >> /usr/bin/$BACKUP_SCRIPT_NAME
       echo '    obnam backup -r $USB_MOUNT/backup/${2} --encrypt-with $MY_BACKUP_KEY_ID ${1}' >> /usr/bin/$BACKUP_SCRIPT_NAME
   else
       # For rsyncrypto usage see http://archive09.linux.com/feature/125322
@@ -3977,8 +3979,10 @@ function backup_directory_to_friend {
       echo -n '$2' >> /usr/bin/$BACKUP_TO_FRIENDS_SCRIPT_NAME
       echo "}')" >> /usr/bin/$BACKUP_TO_FRIENDS_SCRIPT_NAME
 
-      echo -n "  obnam forget --keep=${BACKUP_MAX_DAYS}d " >> /usr/bin/$BACKUP_TO_FRIENDS_SCRIPT_NAME
+      echo '  if [ -d $SERVER_DIRECTORY/backup/${2} ]; then' >> /usr/bin/$BACKUP_TO_FRIENDS_SCRIPT_NAME
+      echo -n "    obnam forget --keep=${BACKUP_MAX_DAYS}d " >> /usr/bin/$BACKUP_TO_FRIENDS_SCRIPT_NAME
       echo '-r $SERVER_DIRECTORY/backup/${2} --encrypt-with $MY_BACKUP_KEY_ID ${1}' >> /usr/bin/$BACKUP_TO_FRIENDS_SCRIPT_NAME
+      echo '  fi' >> /usr/bin/$BACKUP_TO_FRIENDS_SCRIPT_NAME
       echo '  obnam backup -r $SERVER_DIRECTORY/backup/${2} --encrypt-with $MY_BACKUP_KEY_ID ${1}' >> /usr/bin/$BACKUP_SCRIPT_NAME
   else
       # For rsyncrypto usage see http://archive09.linux.com/feature/125322