Comment 8 for bug 1365646

I've narrowed this down a bit. It seems if there's a system update available, and you get prompted to install it (after it's downloaded) and you click "Not now", the update is still left in /android/cache/recovery/.

If you go back into system-settings later, and the latest system-update is still available, and already downloaded, system-image-dbus crashes. I verified this by deleting the downloaded update from /android/cache/recovery/ and restart system-settings. I got prompted to update, and after choosing "Install & restart", everything worked and system-image-dbus left no crash file behind.