Fix bug with mutation search failing when used with celery,
Fix bug with mutation search failing when used with celery,

when multiple occurences of the same mutations where provided

reimandlab/Visualisation-Framework-for-Genome-Mutations,reimandlab/ActiveDriverDB,reimandlab/Visualisation-Framework-for-Genome-Mutations,reimandlab/Visualisation-Framework-for-Genome-Mutations,reimandlab/Visualistion-Framework-for-Genome-Mutations,reimandlab/ActiveDriverDB,reimandlab/ActiveDriverDB,reimandlab/ActiveDriverDB,reimandlab/Visualisation-Framework-for-Genome-Mutations,reimandlab/Visualistion-Framework-for-Genome-Mutations,reimandlab/Visualistion-Framework-for-Genome-Mutations,reimandlab/Visualistion-Framework-for-Genome-Mutations,reimandlab/Visualisation-Framework-for-Genome-Mutations