Something seems to be wrong with caching authority objects by TangoFactory

How to reproduce:

from taurus import Authority, Device

dev = taurus.Device("sys/tg_test/1")
auth = dev.getParentObj()
auth2 = taurus.Authority()  # assuming default schema tango, and an existing default authority
assert auth == auth2, "Two different authority objects"

We should evaluate if these two shouldn't be the same.