Transmitter is a CLI tool for STEEM blockchain witnesses. It quickly allows you to enable/disable your witness or set some properties for the new witness_set_properties call introduced in Hard Fork 20. - announcement post
Suddenly, publish_feed command started giving errors on transmitter. I didn't have much time to investigate the root cause, but it looks like upgrading the Beem dependency and getting rid of the custom chain hack (landed after the chain split) did the job. (Thanks 
If you're a transmitter user, this a necessary upgrade.
Upgrading
Via PIP:
$ pip install transmitter==0.2.7 --upgrade --no-cache
Via Docker:
(Rebuild the container)
$ git pull
$ docker build -t transmitter .
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