// assume virgin repository
byte[] rawHead = Id.fromLong(commitCounter.incrementAndGet())
.getBytes();
head = new Id(rawHead);
Id rootNodeId = pm.writeNode(new MutableNode(this, "/"));
MutableCommit initialCommit = new MutableCommit();
initialCommit.setCommitTS(System.currentTimeMillis());
initialCommit.setRootNodeId(rootNodeId);
pm.writeCommit(head, initialCommit);
pm.writeHead(head);