mix do ecto.migrate doesn't find the ecto.migrate task

[MSch]

This is on Elixir 0.15.1 with ecto 0.2.3

% mix do ecto.migrate --no-start My.Repo, deps.get, deps.compile, compile
** (Mix) The task ecto.migrate could not be found

but those work:

% mix ecto.migrate --no-start My.Repo
% mix do deps.get, deps.compile, compile

(the task lists are just for illustration, I've already compiled everything at the time ecto.migrate isn't found)
(I've filed it for elixir since I guess it's a mix bug)