traffic_server is unable to bind 127.0.0.1:8084 (the default mgmt port) on OSX

When we start up, it errors out binding 8084:

[Mar 1 16:40:33.937] Server

{0x7fff74cdb960} ERROR: Could not bind or listen to port 8084 (error: -1)
[Mar 1 16:40:33.937] Server {0x7fff74cdb960}

WARNING: unable to listen on port 8084: -1 49, Can't assign requested address