Apply label to revision if git refspec is duplicated

[EnigmaCurry]

If you have two revisions with the same git refspec, and you forget to apply a label, they will show up as the same color on the chart. We could automatically apply a label in the case the user forgets about this.

Eg, if revision='apache/cassandra-2.1' and there are multiple revisions with that version, apply labels 'apache/cassandra-2.1 (1)', 'apache/cassandra-2.1 (2)', etc...