$ find * -type f |xargs perl contrib/scripts/spdx.pl
  $ git rm contrib/scripts/spdx.pl

This is inspired by the existing systemd integration, with a few differences:

* This parses the WPAD option, which systemd requested, but did not use.
* We hook into the DAD handling, only making use of the configured address
  once DAD has completed successfully, and declining the lease if it fails.

There are still many areas of possible improvement. In particular, we need
to ensure the parsing of all options are compliant, as n-dhcp4 treats all
options as opaque, unlike sd-dhcp4. We probably also need to look at how
to handle failures and retries (in particular if we decline a lease).

We need to query the current MTU at client startu, as well as the hardware
broadcast address. Both these are provided by the kernel over netlink, so
it should simply be a matter of hooking that up with NM's netlink layer.

Contribution under LGPL2.0+, in addition to stated licenses.

This chunk from nm-device.c is, in fact, okay:

               |<-tab->nm_assert (   !new_config
               |<-tab->           || (   new_config
               |<-tab->               && ({
               |<-tab->                    int ip_ifindex = ...
 empty line -> |
               |<-tab->                    (   ip_ifindex > 0
               |<-tab->                     && ip_ifindex == ...
               |<-tab->                  })));

In continations (that use spaces for alignment), don't allow the number
of leading tabs to change. Previously only removal of tabs was
disallowed, but addition doesn't make sense either, as only spaces
should be used for further alignemnt.

This catches situations like this:

  |<-tab->all_work_and_no_play (makes,
  |<-tab->                      jack,
  |<-tab-><-tab->               a dull boy);

It doesn't have to be at the end of line, there may be more words
following.

Fixes: d66a1ace23c5 ('contrib/checkpatch: avoid command injection in checkpatch.pl script')

The capture variables, $1, etc, are not valid unless the match
succeeded, and they're not cleared, either.

    $ git checkout -B C origin/master && \
        echo XXXXX > f.txt && \
        git add f.txt && \
        git commit -m 'this commit does something()'
    Branch 'C' set up to track remote branch 'master' from 'origin'.
    Reset branch 'C'
    Your branch is up to date with 'origin/master'.
    sh: -c: line 0: syntax error near unexpected token `('
    sh: -c: line 0: `git log --abbrev=12 --pretty=format:"%h ('%s')" -1 does something() 2>/dev/null'

    >>> VALIDATE "a169a98e14 this commit does something()"
    (commit message):4: Commit 'does something()' does not seem to exist:
    > Subject: [PATCH] this commit does something()

    (commit message):4: Refer to the commit id properly: :
    > Subject: [PATCH] this commit does something()

    The patch does not validate.

(cherry picked from commit f8578ddc2e6382d31e1a40b1189ca71cfda427e1)