Some recent runs on the Chromium waterfall have flaked seemingly due to missing blobs, e.g. in https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Fuchsia%20x64/24381 we see ipc_tests and mojo_unittests fail with:

[00019.936] pkgsvr: pkgfs: amber.PackagesActivated([4e372248c4d6a5578c74221363ce928bd31f685b4e872f2dabb896aafde59b5b]) failed: ErrPeerClosed: zx.Channel.Write
[00019.936] pkgsvr: pkgfs: amber.PackagesActivated([2018-11-27 09:08:35,119:INFO:root:Running application.
2018-11-27 09:08:35,230:WARNING:root:Process exited with status code 255.
2018-11-27 09:08:35,231:INFO:root:Terminating kernel log reader.
scp: /data/test_summary.json: No such file or directory
2018-11-27 09:08:35,290:INFO:root:Shutting down QEMU.
4e372248c4d6a5578c74221363ce928bd31f685b4e872f2dabb896aafde59b5b]) failed: ErrBadHandle: zx.Channel.Write
[00020.136] pkgsvr: pkgfs: failed to open package contents at "4e372248c4d6a5578c74221363ce928bd31f685b4e872f2dabb896aafde59b5b": open /blob/4e372248c4d6a5578c74221363ce928bd31f685b4e872f2dabb896aafde59b5b: ErrNotFound: io.directory
mojo_unittests: not found
[00020.136] [ERROR:garnet/lib/loader/package_loader.cc(55)] Could not open directory /pkgfs/packages/mojo_unittests/0 No such file or directory

The CLs included in that run don't appear to include anything specific to Mojo (which both of those suites depend on), but do include a change to //base.