master: --o----o-----o-------o---------------
\ \
\ \
\ \
feature: o----o-----o--o----o<- HEAD
a b c d
Result of this graph should be: ['a', 'b', 'c', 'd']
master: --o----o-----o----o-o------o--------------
\ \ \
\ \ \
\ \ \
feature: o----o-----o-----o--o----o<- HEAD
a b c d
Result of this graph should too be: ['a', 'b', 'c', 'd']