distributed: Fix two ServerRepository issues in Python 3

direct/src/distributed/ServerRepository.py

@@ -628,7 +628,7 @@ class ServerRepository:
         del self.clientsByConnection[client.connection]
         del self.clientsByDoIdBase[client.doIdBase]
 
-        id = client.doIdBase / self.doIdRange
+        id = client.doIdBase // self.doIdRange
         self.idAllocator.free(id)
 
         self.qcr.removeConnection(client.connection)
@@ -689,7 +689,7 @@ class ServerRepository:
     def clientHardDisconnectTask(self, task):
         """ client did not tell us he was leaving but we lost connection to
         him, so we need to update our data and tell others """
-        for client in self.clientsByConnection.values():
+        for client in list(self.clientsByConnection.values()):
             if not self.qcr.isConnectionOk(client.connection):
                 self.handleClientDisconnect(client)
         return Task.cont