I had to reimage my desktop (aside: by default goobuntu-backup does not backup .git repos, which means it is useless for backing up your checkout; this is an unpleasant surprise).

$ mkdir chromiumos

$ cd chromiumos

$ repo init -u https://chrome-internal.googlesource.com/chromeos/manifest-internal.git --repo-url='https://chromium.googlesource.com/external/repo.git'

$ repo sync
<a whole lot of spew, and a lot of time waiting for chromiumos/third_party/kernel>

Your repo was successfully initialized

<repo pauses with no output for several minutes, but without terminating, making it very tempting to CTRL+C it; however, no actual git checkouts have been created, and ls shows an empty checkout>

<a bunch more spew and multi-minute periods of silence>

Your sources have been sync'd successfully.


<script returns finally, and checkout exists as expected>