It's a pretty long story. If you want to read all of it, you probably need to read the entire debian-devel and debian-ctte archives from approximately a year and a half ago until February/March this year.
A shorter summary is something like (from my memory, coloured by my views, etc, but I believe it's largely correct). User names are generally @debian.org, finger $email@example.com for full names and such. It's a bit rambling and written in one go, but it's what you get this time:
- I upload systemd to Debian about a month after its initial release, get it into a ok-ish shape for wheezy, but not anywhere near suitable for being the default.
- Other distros start switching to systemd as default, various people in Debian start discussing if we should switch to systemd. Some people say yes, some no, some want to switch to upstart. Bickering and discussions in equal measure spread out across all media (IRC, blogs/planet, mailing lists, in-person discussions). Most of it reasonably civil.
- At some point, paultag files https://bugs.debian.org/cgi-bi... (_massive_ bug report, you don't want to read it all) , asking the Debian technical committee to default on what the default should be.
- Lots of discussions happen, we use a bit of liw's and rra's Essay Debate System (https://wiki.debian.org/Debate, https://wiki.debian.org/Debate...) to structure the debate. It's Debian, it has to be A System.
- vorlon (Steve Langasek) sets up VMs using the various init systems for the Technical Committee members to play with. They do so and write up their findings and arguments. rra's writeup is at https://lists.debian.org/debia... and is possibly the best comparison I've ever read of init systems. Lots more discussions happen. I contribute a fair bit with my systemd maintainer hat on (though we're at this point a team maintaining systemd in Debian) and is very happy this happens while I'm holidaying in Spain so I don't have to deal with a day job at the same time.
- A lot of arguing internally to the CTTE whether to couple the question of what the default init system should be with whether it's ok for packages to require a given init system. bdale resolves the knot by calling for votes on a proposal very quickly after proposing a ballot. iwj sees this as backstabbing and is still very, very angry about this to this day.
The vote ends with systemd being the winner, after bdale's casting vote as the CTTE chair.
After this, there is an attempted General Resolution in March, which fails to get enough seconds, this is restarted by iwj on late October this year. The goal of this GR appears to be to forbid packages to depend on a specific init system.