Allow multiple identical sources

The source-repositories element puts source in place in the generated image
for later installation.  It is possible for two elements to define the same
source to later install, and as long as the remote location and reference to be
installed is identical, we should not error.

Change-Id: Ic7dfb1961486c59d2005b5c1e7587267ea42e999
Update RHEL Registration

This patch updates the 00-rhel-registration script to not
not fail a stack when metadata isn't found.

Change-Id: Ie305fed79e4baadf1a03c4a3d06a23cf36e92f77
Check python with flake8 instead of dib-lint

We check python files with dib-lint rather than flake8 which have
conflicting opinions. This means weve been (forcibly) writing non pep8
python.

Also fixing pep8 issues so tests pass.

Change-Id: Idc9db40334f6e15738a7802c06697270df68741c
Fail helpfully if no elements are specified

Instead of charging ahead and failing because we lack dib-run-parts we
can fail in this case with a useful error message.

Change-Id: Ie10176b5a7019a0385796984ebbaf7742876925a
Make some pkg-map errors soft

An app using pkg-map (like package-installs) might want to distinguish
between a hard error (invalid pkg-map file) and a soft error (no
mapping found). Currently this is not possible because we only return
with error values of 1.

Also printing error messages to stderror so we can still make use of
stdout data during a soft error.

Change-Id: I8bef56d3a74e8530afb8c58ac50ca3e9f7700639
Merge "Check python with flake8 instead of dib-lint"
Merge "Make some pkg-map errors soft"
Warning when using pypi element without a mirror

Using only a local filesystem mirror could lead opaque errors.
Print a warning message in this situations.

Change-Id: I5f77151ea928868f4c441e8a1bb2eb0966b21832
Closes-Bug: #1297948
Merge "Fail helpfully if no elements are specified"
disk-image-create: fix test when no argument is given.

Avoid a warning when multiple arguments are passed to disk-image-create
like:

bin/disk-image-create: 146: [: aa: unexpected operator

Change-Id: I619d7bf2e4b56885d629019b80b249bc80b8f43e
Merge "Update RHEL Registration"
Merge "Warning when using pypi element without a mirror"
Merge "Allow multiple identical sources"
Remove use of sudo from yum pre and post elements

sudo is not needed, since in-chroot elements are run in the context
of the root user. Furthermore, sudo in pre-install is problematic as
sudo may not have been installed yet (imagine a debootstrap build)

Change-Id: Ib5c7e176a90fe3b8fa9c3cd702d3d815df54f472
Remove the grub2 install from redhat-common

We immediately remove this, but the -grub2 causes a later attempt to
remove it again which fails. Don't install it in the first place.

Change-Id: I31d64abc9596707bdb8a0505d0dcbf7b82e1b82d
Unset requiretty if it exists in sudoers

Fedora sets requiretty globally by default. This makes sense for
interactive machines with lots of password typing, but is pretty
attrocious for machines that might need users who remotely sudo to do
things. Just remove the setting.

Change-Id: Ic32bd92061a73f854683cc0d2d8919071dabe8cf
Merge "Unset requiretty if it exists in sudoers"
Merge "disk-image-create: fix test when no argument is given."
Merge "Remove use of sudo from yum pre and post elements"
Merge "Remove the grub2 install from redhat-common"