amd64-generic-goma-canary-chromium-pfq-informational has been failing at the step of "InitSDK" since the following build:
https://cros-goldeneye.corp.google.com/chromeos/healthmonitoring/buildDetails?buildbucketId=8937373519504081440

libbrillo-0.0.1-r1358: fatal: destination path '/var/tmp/portage/chromeos-base/libbrillo-0.0.1-r1358/work/libbrillo-0.0.1/platform2/libbrillo' already exists and is not an empty directory.
libbrillo-0.0.1-r1358:  * ERROR: chromeos-base/libbrillo-0.0.1-r1358::chromiumos failed (unpack phase):
libbrillo-0.0.1-r1358:  *   Can't clone /mnt/host/source/src/aosp/external/libbrillo.
libbrillo-0.0.1-r1358:  * 
libbrillo-0.0.1-r1358:  * Call stack:
libbrillo-0.0.1-r1358:  *     ebuild.sh, line  133:  Called src_unpack
libbrillo-0.0.1-r1358:  *   environment, line 3768:  Called platform_src_unpack
libbrillo-0.0.1-r1358:  *   environment, line 3339:  Called cros-workon_src_unpack
libbrillo-0.0.1-r1358:  *   environment, line  959:  Called die
libbrillo-0.0.1-r1358:  * The specific snippet of code:
libbrillo-0.0.1-r1358:  *                       git clone -sn "${path[i]}" "${destdir[i]}" || die "Can't clone ${path[i]}.";
libbrillo-0.0.1-r1358:  * 
libbrillo-0.0.1-r1358:  * If you need support, post the output of `emerge --info '=chromeos-base/libbrillo-0.0.1-r1358::chromiumos'`,
libbrillo-0.0.1-r1358:  * the complete build log and the output of `emerge -pqv '=chromeos-base/libbrillo-0.0.1-r1358::chromiumos'`.
libbrillo-0.0.1-r1358:  * The complete build log is located at '/var/log/portage/chromeos-base:libbrillo-0.0.1-r1358:20180823-195902.log'.
libbrillo-0.0.1-r1358:  * For convenience, a symlink to the build log is located at '/var/tmp/portage/chromeos-base/libbrillo-0.0.1-r1358/temp/build.log'.
libbrillo-0.0.1-r1358:  * The ebuild environment file is located at '/var/tmp/portage/chromeos-base/libbrillo-0.0.1-r1358/temp/environment'.
libbrillo-0.0.1-r1358:  * Working directory: '/var/tmp/portage/chromeos-base/libbrillo-0.0.1-r1358/work'
libbrillo-0.0.1-r1358:  * S: '/var/tmp/portage/chromeos-base/libbrillo-0.0.1-r1358/work/libbrillo-0.0.1'
libbrillo-0.0.1-r1358: >>> Failed to emerge chromeos-base/libbrillo-0.0.1-r1358, Log file:
libbrillo-0.0.1-r1358: >>>  '/var/log/portage/chromeos-base:libbrillo-0.0.1-r1358:20180823-195902.log'