Adding your own custom bridges generates a parsing error

In Tor Browser alpha (9.0a8), if I add a custom bridge starting with Bridge:

Bridge obfs4 IP:Port cert

It gives me a parsing error:

10/16/19, 13:22:41.785 [WARN] Error parsing Bridge address 'obfs4'

But it works if I add directly:"obfs4 IP:Port cert..."

In Tor Browser stable it works both ways (Bridge and only obfs4).