Comment 2 for bug 1571569

This got fixed in xenial, so closing:

Setting up udev (229-4ubuntu4) ...
addgroup: The group `input' already exists as a system group. Exiting.
A chroot environment has been detected, udev not started.

I confirm the issue for trusty. However, if you want to work with chroots you really need to create a policy-rc.d to disable starting of services. If you don't, then pretty well any package that tries to start a service will actually do/attempt so, which is often failing and usually undesirable in such chroots. mk-sbuild and similar tools create this automatically, but the simplest form is

/usr/sbin/policy-rc.d:
  #!/bin/sh
  exit 101

See man invoke-rc.d and https://people.debian.org/~hmh/invokerc.d-policyrc.d-specification.txt