makeCluster behaves strangely with repeated notes

[Gilberto Agostinho]

When more than two notes are repeated, makeCluster creates some strange 
shapes. To observe that, it's necessary to reduce the 
ClusterSpanner.padding. See:

\version "2.19.15"

% all fine with single note repetitions
\makeClusters {
  \override ClusterSpanner.padding = #'-0.25
  c'1
  c'
}

% all fine when a rest is in between repeated notes
\makeClusters {
  \override ClusterSpanner.padding = #'-0.25
  c'1
  s
  c'
}

% strange behaviour when more than 2 notes are repeated
\makeClusters {
  \override ClusterSpanner.padding = #'-0.25
  c'1
  c'
  c'
}

This behaviour is not present when dealing with chords.

Let me know if more information is needed about this potential bug.

Best,
Gilberto