Nest: Allow modification of channels inherited from templates

Multiple definitions of same channels are forbidden, but inherited
channel can be redefined. In such case channel options are merged.
32 jobs for <span class="ref-name">int-new</span> in 6 minutes and 55 seconds (queued for 8 seconds)
Status Job ID Name Coverage
  Image
passed #96494
dind allowed to fail
docker_centos-6-amd64

00:00:26

passed #96495
dind allowed to fail
docker_centos-7-amd64

00:00:26

passed #96484
dind allowed to fail
docker_debian-7-amd64

00:00:36

passed #96488
dind allowed to fail
docker_debian-7-i386

00:00:41

passed #96485
dind allowed to fail
docker_debian-8-amd64

00:00:40

passed #96489
dind allowed to fail
docker_debian-8-i386

00:00:30

passed #96486
dind allowed to fail
docker_debian-9-amd64

00:00:38

passed #96490
dind allowed to fail
docker_debian-9-i386

00:00:30

passed #96487
dind allowed to fail
docker_debian-testing-amd64

00:00:41

passed #96491
dind allowed to fail
docker_debian-testing-i386

00:00:31

passed #96492
dind allowed to fail
docker_fedora-25-amd64

00:00:31

passed #96493
dind allowed to fail
docker_fedora-26-amd64

00:00:32

passed #96496
dind allowed to fail
docker_opensuse-42_3-amd64

00:00:58

passed #96497
dind allowed to fail
docker_ubuntu-14_04-amd64

00:00:57

passed #96498
dind allowed to fail
docker_ubuntu-16_04-amd64

00:00:57

 
  Build
passed #96505
docker linux amd64
build-centos-6-amd64

00:00:38

passed #96506
docker linux amd64
build-centos-7-amd64

00:01:21

passed #96499
docker linux amd64
build-debian-7-amd64

00:00:40

passed #96510
docker linux amd64
build-debian-7-i386

00:01:27

passed #96500
docker linux amd64
build-debian-8-amd64

00:01:29

passed #96511
docker linux amd64
build-debian-8-i386

00:00:46

passed #96501
docker linux amd64
build-debian-9-amd64

00:00:45

passed #96512
docker linux amd64
build-debian-9-i386

00:01:52

passed #96502
docker linux amd64
build-debian-testing-amd64

00:01:37

passed #96513
docker linux amd64
build-debian-testing-i386

00:00:47

passed #96503
docker linux amd64
build-fedora-25-amd64

00:00:42

passed #96504
docker linux amd64
build-fedora-26-amd64

00:01:27

passed #96514
freebsd amd64
build-freebsd-11-amd64

00:04:22

passed #96515
freebsd i386
build-freebsd-11-i386

00:04:27

passed #96507
docker linux amd64
build-opensuse-42_3-amd64

00:00:40

passed #96508
docker linux amd64
build-ubuntu-14_04-amd64

00:01:26

passed #96509
docker linux amd64
build-ubuntu-16_04-amd64

00:00:42