Improve error reporting of too much free space

ipam/ring/ring.go

@@ -40,7 +40,6 @@ var (
 	ErrInvalidEntry     = errors.New("Received invalid state update!")
 	ErrEntryInMyRange   = errors.New("Received new entry in my range!")
 	ErrNoFreeSpace      = errors.New("No free space found!")
-	ErrTooMuchFreeSpace = errors.New("Entry reporting too much free space!")
 	ErrInvalidTimeout   = errors.New("dt must be greater than 0")
 	ErrNotFound         = errors.New("No entries for peer found")
 )
@@ -76,7 +75,7 @@ func (r *Ring) checkInvariants() error {
 		distance := r.distance(entry.Token, next.Token)
 
 		if entry.Free > distance {
-			return ErrTooMuchFreeSpace
+			return fmt.Errorf("Entry %s-%s reporting too much free space: %d > %d", entry.Token, next.Token, entry.Free, distance)
 		}
 	}