[lib] kwollect - fix issue with hash merging

data/grid5000/sites/grenoble/clusters/dahu/dahu.json

data/grid5000/sites/grenoble/clusters/troll/troll.json

data/grid5000/sites/grenoble/clusters/yeti/yeti.json

data/grid5000/sites/lille/clusters/chetemi/chetemi.json

data/grid5000/sites/lille/clusters/chiclet/chiclet.json

data/grid5000/sites/lille/clusters/chifflet/chifflet.json

data/grid5000/sites/lille/clusters/chifflot/chifflot.json

...00/sites/luxembourg/clusters/petitprince/petitprince.json

data/grid5000/sites/lyon/clusters/gemini/gemini.json

data/grid5000/sites/lyon/clusters/hercule/hercule.json

data/grid5000/sites/lyon/clusters/nova/nova.json

data/grid5000/sites/lyon/clusters/orion/orion.json

data/grid5000/sites/lyon/clusters/pyxis/pyxis.json

data/grid5000/sites/lyon/clusters/taurus/taurus.json

data/grid5000/sites/nancy/clusters/graffiti/graffiti.json

data/grid5000/sites/nancy/clusters/graoully/graoully.json

data/grid5000/sites/nancy/clusters/graphique/graphique.json

data/grid5000/sites/nancy/clusters/graphite/graphite.json

data/grid5000/sites/nancy/clusters/grcinq/grcinq.json

data/grid5000/sites/nancy/clusters/grele/grele.json