Most trybots on R69 fail with the following error.

chromeos-chrome-69.0.3497.45_rc-r1: >>> Preparing source in /build/zoombini/tmp/portage/chromeos-base/chromeos-chrome-69.0.3497.45_rc-r1/work/chromeos-chrome-69.0.3497.45_rc ...
chromeos-chrome-69.0.3497.45_rc-r1:  * /var/cache/chromeos-cache/distfiles/target/chrome-src-internal should be set here properly
chromeos-chrome-69.0.3497.45_rc-r1: /build/zoombini/tmp/portage/chromeos-base/chromeos-chrome-69.0.3497.45_rc-r1/temp/environment: line 4405: cd: /var/cache/chromeos-cache/distfiles/target/chrome-src-internal/src: No such file or directory
chromeos-chrome-69.0.3497.45_rc-r1:  * ERROR: chromeos-base/chromeos-chrome-69.0.3497.45_rc-r1::chromiumos failed (prepare phase):
chromeos-chrome-69.0.3497.45_rc-r1:  *   Cannot chdir to /var/cache/chromeos-cache/distfiles/target/chrome-src-internal
chromeos-chrome-69.0.3497.45_rc-r1:  * 
chromeos-chrome-69.0.3497.45_rc-r1:  * Call stack:
chromeos-chrome-69.0.3497.45_rc-r1:  *     ebuild.sh, line 133:  Called src_prepare
chromeos-chrome-69.0.3497.45_rc-r1:  *   environment, line 4405:  Called die
chromeos-chrome-69.0.3497.45_rc-r1:  * The specific snippet of code:
chromeos-chrome-69.0.3497.45_rc-r1:  *       cd "${CHROME_ROOT}/src" || die "Cannot chdir to ${CHROME_ROOT}";

Examples:
https://cros-goldeneye.corp.google.com/chromeos/healthmonitoring/buildDetails?buildbucketId=8937931221109914064
https://cros-goldeneye.corp.google.com/chromeos/healthmonitoring/buildDetails?buildbucketId=8937931227613400256
https://cros-goldeneye.corp.google.com/chromeos/healthmonitoring/buildDetails?buildbucketId=8937931224508229776
https://cros-goldeneye.corp.google.com/chromeos/healthmonitoring/buildDetails?buildbucketId=8937931226625460112
https://cros-goldeneye.corp.google.com/chromeos/healthmonitoring/buildDetails?buildbucketId=8937931225211505616
https://cros-goldeneye.corp.google.com/chromeos/healthmonitoring/buildDetails?buildbucketId=8937931223679058384