I'm trying to pull in the dev-util/bcc ebuild from upstream but it's failing to find the tarball on our local mirrors.

$ cros_portage_upgrade --upgrade --board=amd64-generic dev-util/bcc --unstable-ok
You have selected boards for archs ['amd64'], which does not cover all standard archs ['amd64', 'arm']
If you continue with this upgrade you may break builds for architectures not covered by your
boards.  Continue only if you have a reason to limit this upgrade to these specific architectures.


Do you want to continue anyway? (yes/No)? yes
Updating previously created upstream cache at /tmp/portage.
Fetching origin
Running with board amd64-generic.
Resolved "dev-util/bcc" to "dev-util/bcc-0.7.0" (upstream).
Copying dev-util/bcc-0.7.0 from upstream.
Failed "ebuild manifest" for upgraded package.
Output of u'ebuild /mnt/host/source/src/third_party/portage-stable/dev-util/bcc/bcc-0.7.0.ebuild manifest':
>>> Downloading 'https://commondatastorage.googleapis.com/chromeos-localmirror/distfiles/bcc-0.7.0.tar.gz'
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
curl: (22) The requested URL returned error: 404 Not Found
>>> Downloading 'https://commondatastorage.googleapis.com/chromeos-mirror/gentoo/distfiles/bcc-0.7.0.tar.gz'
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
curl: (22) The requested URL returned error: 404 Not Found
!!! Couldn't download 'bcc-0.7.0.tar.gz'. Aborting.
!!! Fetch failed for bcc-0.7.0.tar.gz, can't update Manifest


To reset all changes in /mnt/host/source/src/third_party/portage-stable now:
 cd /mnt/host/source/src/third_party/portage-stable; git reset --hard; cd -
Keeping upstream cache at /tmp/portage.
Failed with above errors.

Is our mirror no longer working?