This feature is broken and doesn't work properly in all scenarios.
e.g. if we have the following DAGs:
client server
D draft
C draft C draft
B draft B public
A public A public
The current code would only send the phase data for C. The
client wouldn't see that B moved from draft to public.
This feature will be restored in a future commit. For now, it is
making refactoring of how revisions are specified in the wire protocol
a bit difficult...