Add check to prevent division by zero during backup status

management/backup.py

@@ -115,7 +115,7 @@ def backup_status(env):
 	# full backup. That full backup frees up this one to be deleted. But, the backup
 	# must also be at least min_age_in_days old too.
 	deleted_in = None
-	if incremental_count > 0 and first_full_size is not None:
+	if incremental_count > 0 and incremental_size > 0 and first_full_size is not None:
 		# How many days until the next incremental backup? First, the part of
 		# the algorithm based on increment sizes:
 		est_days_to_next_full = (.5 * first_full_size - incremental_size) / (incremental_size/incremental_count)