Deleted and recreated repositories keep old sivas on disk but delete its references #371

Some repositories are recreated frequently so it's init commit changes. This leaves siva files from old repository versions dangling, not pointed by any reference. Example of repository:

https://github.com/testingqaskope/Automation_donot_delete
ID: 016497c9-037f-acf2-b0f6-3bd3ff5bb4e7
Roots:

• c898f2aae64c75143b9894135bb2575fdfee2377
• 0e75519232d148811a27600c59af18d78ed6062d
• 022508a67387dd8d3c44d5ce85e38949279a5244
• 0379922fbf616ec819cf50ce6a9c57761a907100
• 56ace70340af4dfe884115095ec7ef3f727cebf9