Circular hash collision where digest is pre-image: Could hash(a) = b, hash(b)=c, then hash(c)=a?
We like to think of hash functions as random functions, and there is no reason a random function shouldn't have a cycle of size 3 which is what you describe.
Obviously it would be very difficult to find such a cycle, we can discuss how likely is it a random function over space size $n$ has a cycle of size 3. 

Ignoring cycles of size 1 and 2 which acount for a small portion of the space we have $n/3$ independent size 3 prefixes. each of these has probability $1/n$ to close a size 3 cycle. the chance they all miss is $(1-1/n)^{(n/3)}$ which is $(1/e)^{(1/3)}$ or 0.71653131057.
so the chance of at least 1 such cycle is 28% which is consistent with simulation results in comments above by poncho.