Encapsulated DHCP options are not supported in neutron

[Brian Haley]

Some PXE implementations, including iPXE, use vendor-specific options
encapsulated in a single top-level option to send configuration data in
DHCP packets. As an example, iPXE encapsulates various options in option
175.

This is fully supported by dnsmasq (see below), however, the original
code which translates a DHCP option name and value into a dnsmasq
command-line argument would expect any non-numeric option 'name' to be a
named option, hence prepending with `option:`.

The dhcp agent should be changed to ensure `encap:X,Y` is properly translated
into either `encap:X,Y` if Y is numerical, or `encap:X,option:Y` if Y is text.

[Lajos Katona (lajos-katona)]

For some reason launchpad missed the proposed fix for this one:
https://review.opendev.org/681466

[Slawek Kaplonski (slaweq)]

This bug has had a related patch abandoned and has been automatically un-assigned due to inactivity. Please re-assign yourself if you are continuing work or adjust the state as appropriate if it is no longer valid.

[OpenStack Infra (hudson-openstack)]

Change abandoned by Slawek Kaplonski (<email address hidden>) on branch: master
Review: https://review.opendev.org/681466
Reason: This review is > 4 weeks without comment, and failed Zuul jobs the last time it was checked. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and leaving a 'recheck' comment to get fresh test results.