Merge remote-tracking branch 'nl6720/fix-unbound-variables-in-_validate_options'

* nl6720/fix-unbound-variables-in-_validate_options:
  mkarchiso: error out of iso and netboot build modes if no boot modes are specified
  mkarchiso: split out build mode specific checks from _validate_options to _validate_requirements_buildmode_*
  mkarchiso: fix unbound variable errors in _validate_options
7 jobs for master in 41 minutes and 18 seconds (queued for 8 seconds)
Status Name Job ID Coverage
  Check
passed check #32425

00:00:13

 
  Build
passed build_long: [baseline iso] #32428
fast-single-thread

00:17:44

passed build_long: [baseline netboot] #32429
fast-single-thread

00:17:04

passed build_long: [releng iso] #32430
fast-single-thread

00:41:02

passed build_long: [releng netboot] #32431
fast-single-thread

00:39:40

passed build_short: [baseline bootstrap] #32426

00:13:16

passed build_short: [releng bootstrap] #32427

00:13:30