pxeconfig() doesn't handle the case where there is no sane latest boot image correctly

[Graham Binns]

At present, pxeconfig() handles finding no sane boot series for a given set of (nodegroup, arch, subarch, release, purpose) by setting the latest label to "no-such-image". This is mainly for the sake of tests, because such a situation should never arise in the real world.

However, the best way to handle this would be to raise an exception and let both client and server handle it correctly. The current functionality is a stop-gap to allow us to land the code without breaking the test suite.

[Michael Hudson-Doyle (mwhudson)]

I think this problem is why commissioning midway fails currently: the fetch of pxelinux.cfg/default-arm-highbank should fail (and proceed to pxelinux.cfg/default-arm, which should but does not currently return something sensible) but instead it returns a pxelinux config file that doesn't work.

[Michael Hudson-Doyle (mwhudson)]

IOW, if you care about commissioning armhf (not clear if you should...), then this is higher priority than Medium.