I just got your most recent update to your SageTV container and noticed how many steps it has. It is highly recommended to have as few steps as possible. I noticed in your sagetv-base that you have a whole bunch of ADD and RUN lines for each individual my_init script. Since they are all in the same folder I would do it like this:

ADD init.d/ /etc/my_init.d/
RUN chmod 755 /etc/my_init.d/*

Turns 26 steps into 2.

In fact, if you create a single folder like "image" that duplicates where all your files will go in the resulting image you can create a line like:

ADD image/ /

and in one step all the required files are in there and all you need to do is chmod them.

Sorry, meant this as a private message.