coreboot fails to boot for falco peppy and samus (and maybe others) since Dec 20th. 

here is an example from today:

https://cros-goldeneye.corp.google.com/chromeos/healthmonitoring/buildDetails?buildbucketId=8925962903461109408

sample error:

coreboot-0.0.1-r2842: make: *** No rule to make target '3rdparty/blobs/mainboard/google/falco/vgabios.bin', needed by 'build/coreboot.pre'.  Stop.
  coreboot-0.0.1-r2842: make: *** Waiting for unfinished jobs....
  coreboot-0.0.1-r2842:     MICROCODE  cpu_microcode_blob.bin
  coreboot-0.0.1-r2842: 3rdparty/blobs/cpu/intel/model_306cx/microcode.bin 3rdparty/blobs/cpu/intel/model_4065x/microcode.bin
  coreboot-0.0.1-r2842: Package yaml-0.1 was not found in the pkg-config search path.
  coreboot-0.0.1-r2842: Perhaps you should add the directory containing `yaml-0.1.pc'
  coreboot-0.0.1-r2842: to the PKG_CONFIG_PATH environment variable
  coreboot-0.0.1-r2842: No package 'yaml-0.1' found
  coreboot-0.0.1-r2842: Package yaml-0.1 was not found in the pkg-config search path.
  coreboot-0.0.1-r2842: Perhaps you should add the directory containing `yaml-0.1.pc'
  coreboot-0.0.1-r2842: to the PKG_CONFIG_PATH environment variable
  coreboot-0.0.1-r2842: No package 'yaml-0.1' found
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2api.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2common.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2api.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2crc8.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2api.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2common.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2misc.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2common.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2crc8.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2nvstorage.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2crc8.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2misc.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2misc.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2rsa.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2nvstorage.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2nvstorage.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2secdata.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2rsa.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2rsa.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2secdatak.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2secdata.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2secdata.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2sha1.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2secdatak.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2sha256.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2secdatak.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2sha1.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2sha512.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2sha1.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2sha256.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2sha_utility.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2sha256.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2sha512.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2tpm_bootmode.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2sha512.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2sha_utility.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2hmac.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2tpm_bootmode.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2sha_utility.o
  coreboot-0.0.1-r2842:     CC            firmware/lib20/api.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2hmac.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2tpm_bootmode.o
  coreboot-0.0.1-r2842:     CC            firmware/lib20/api_kernel.o
  coreboot-0.0.1-r2842:     CC            firmware/2lib/2hmac.o
  coreboot-0.0.1-r2842:     CC            firmware/lib20/api.o
  coreboot-0.0.1-r2842:     CC            firmware/lib20/common.o
  coreboot-0.0.1-r2842:     CC            firmware/lib20/api.o
  coreboot-0.0.1-r2842:     CC            firmware/lib20/api_kernel.o
  coreboot-0.0.1-r2842:     CC            firmware/lib20/kernel.o
  coreboot-0.0.1-r2842:     CC            firmware/lib20/api_kernel.o
  coreboot-0.0.1-r2842:     CC            firmware/lib20/common.o
  coreboot-0.0.1-r2842:     CC            firmware/lib20/misc.o
  coreboot-0.0.1-r2842:     CC            firmware/lib20/common.o
  coreboot-0.0.1-r2842:     CC            firmware/lib20/kernel.o
  coreboot-0.0.1-r2842:     CC            firmware/lib20/packed_key.o
  coreboot-0.0.1-r2842:     CC            firmware/lib20/kernel.o
  coreboot-0.0.1-r2842:     CC            firmware/lib20/misc.o
  coreboot-0.0.1-r2842:     CC            firmware/lib20/packed_key.o
  coreboot-0.0.1-r2842:     CC            firmware/lib20/misc.o
  coreboot-0.0.1-r2842:     CC            firmware/lib20/packed_key.o
  coreboot-0.0.1-r2842:     RM            vboot_fw20.a
  coreboot-0.0.1-r2842:     AR            vboot_fw20.a
  coreboot-0.0.1-r2842:     RM            vboot_fw20.a
  coreboot-0.0.1-r2842:     AR            vboot_fw20.a
  coreboot-0.0.1-r2842:     RM            vboot_fw20.a
  coreboot-0.0.1-r2842:     AR            vboot_fw20.a
  coreboot-0.0.1-r2842:  * ERROR: sys-boot/coreboot-0.0.1-r2842::chromiumos failed (compile phase):
  coreboot-0.0.1-r2842:  *   emake failed
  coreboot-0.0.1-r2842:  * 
  coreboot-0.0.1-r2842:  * If you need support, post the output of `emerge --info '=sys-boot/coreboot-0.0.1-r2842::chromiumos'`,
  coreboot-0.0.1-r2842:  * the complete build log and the output of `emerge -pqv '=sys-boot/coreboot-0.0.1-r2842::chromiumos'`.
  coreboot-0.0.1-r2842:  * The complete build log is located at '/build/falco/tmp/portage/logs/sys-boot:coreboot-0.0.1-r2842:20181227-123713.log'.
  coreboot-0.0.1-r2842:  * For convenience, a symlink to the build log is located at '/build/falco/tmp/portage/sys-boot/coreboot-0.0.1-r2842/temp/build.log'.
  coreboot-0.0.1-r2842:  * The ebuild environment file is located at '/build/falco/tmp/portage/sys-boot/coreboot-0.0.1-r2842/temp/environment'.
  coreboot-0.0.1-r2842:  * Working directory: '/build/falco/tmp/portage/sys-boot/coreboot-0.0.1-r2842/work/coreboot-0.0.1'
  coreboot-0.0.1-r2842:  * S: '/build/falco/tmp/portage/sys-boot/coreboot-0.0.1-r2842/work/coreboot-0.0.1'
  coreboot-0.0.1-r2842: >>> Failed to emerge sys-boot/coreboot-0.0.1-r2842 for /build/falco/, Log file:
  coreboot-0.0.1-r2842: >>>  '/build/falco/tmp/portage/logs/sys-boot:coreboot-0.0.1-r2842:20181227-123713.log'
  coreboot-0.0.1-r2842: 
  coreboot-0.0.1-r2842:  * Messages for package sys-boot/coreboot-0.0.1-r2842 merged to /build/falco/:
  coreboot-0.0.1-r2842:  * Log file: /build/falco/tmp/portage/logs/sys-boot:coreboot-0.0.1-r2842:20181227-123713.log
  coreboot-0.0.1-r2842: 
  coreboot-0.0.1-r2842:  * ERROR: sys-boot/coreboot-0.0.1-r2842::chromiumos failed (compile phase):
  coreboot-0.0.1-r2842:  *   emake failed
  coreboot-0.0.1-r2842:  * 
  coreboot-0.0.1-r2842:  * If you need support, post the output of `emerge --info '=sys-boot/coreboot-0.0.1-r2842::chromiumos'`,
  coreboot-0.0.1-r2842:  * the complete build log and the output of `emerge -pqv '=sys-boot/coreboot-0.0.1-r2842::chromiumos'`.
  coreboot-0.0.1-r2842:  * The complete build log is located at '/build/falco/tmp/portage/logs/sys-boot:coreboot-0.0.1-r2842:20181227-123713.log'.
  coreboot-0.0.1-r2842:  * For convenience, a symlink to the build log is located at '/build/falco/tmp/portage/sys-boot/coreboot-0.0.1-r2842/temp/build.log'.
  coreboot-0.0.1-r2842:  * The ebuild environment file is located at '/build/falco/tmp/portage/sys-boot/coreboot-0.0.1-r2842/temp/environment'.
  coreboot-0.0.1-r2842:  * Working directory: '/build/falco/tmp/portage/sys-boot/coreboot-0.0.1-r2842/work/coreboot-0.0.1'
  coreboot-0.0.1-r2842:  * S: '/build/falco/tmp/portage/sys-boot/coreboot-0.0.1-r2842/work/coreboot-0.0.1'