Several of the chrome-pfq waterfall buildbots on the ChromeOS internal waterfall are failing in BuildPackages, while attempting to build Chrome, with the error:

ninja: error: unknown target 'khronos_glcts_test'

chromeos-chrome-53.0.2781.0_rc-r1: >>> Compiling source in /build/daisy_skate/tmp/portage/chromeos-base/chromeos-chrome-53.0.2781.0_rc-r1/work/chromeos-chrome-53.0.2781.0_rc ...
chromeos-chrome-53.0.2781.0_rc-r1: ninja: Entering directory `c/Release'
chromeos-chrome-53.0.2781.0_rc-r1: ninja: error: unknown target 'khronos_glcts_test'
chromeos-chrome-53.0.2781.0_rc-r1:  * ERROR: chromeos-base/chromeos-chrome-53.0.2781.0_rc-r1::chromiumos failed (compile phase):
chromeos-chrome-53.0.2781.0_rc-r1:  *   (no error message)
chromeos-chrome-53.0.2781.0_rc-r1:  * 


See the following example builds that have failed this way:
https://uberchromegw.corp.google.com/i/chromeos/builders/peach_pit-chrome-pfq/builds/2218
https://uberchromegw.corp.google.com/i/chromeos/builders/veyron_minnie-cheets-chrome-pfq/builds/353https://uberchromegw.corp.google.com/i/chromeos/builders/daisy_skate-chrome-pfq/builds/2569