Code review comment for lp://staging/~paelzer/curtin/bug-1574113-derived-repositories

Started a vmtest run at
https://server-team-jenkins.canonical.com/job/curtin-vmtest-venonat-devel/33/

I dont think we have 'preserve_sources_list' implemented as intended.

Our doc says:
|  preserve_sources_list: <true|false|keep>
|    # For cloud-init this defaults to false. By default, cloud-init renders
|    # /etc/apt/sources.list from its provided templates on first boot.
|    # For Curtin this defaults to false. By default, curtin will always attempt to
|    # replace mirrors inside the sources.list it finds in the image.
|    # Curtin will configure cloud-init in the target via
|    # /etc/cloud/cloud.cfg.d/curtin-preserve-sources.list with True,
|    # which causes cloud-init to not touch /etc/apt/sources.list by default.
|    # Unless explicitly  requested by cloud-init userdata (overwriting to False).
|    # Effectively this changes the default from False to True

I thought that in discussion you and I had agreed that this was in fact 'boolean', and that curtin would *always* replace /etc/apt/sources.list . I'm not terribly opposed to a tri-state, where it can be told to leave it untouched though.

That said, i do not see where curtin is configuring cloud-init in the target to set. curtin should always set cloud-init to preserve sources.list unless there is another use case that i'm missing.

I'm not done with the review yet, but wanted to hit 'submit' before losing context and losing what i had done.