Unknown Error Download failed when running `mbed new mbed-classic-program --mbedlib`

When trying to create a new mbed 2 project using mbed CLI, according to the documentation:
`mbed new mbed_2_project --mbedlib`

I get the following error message:

```
[mbed] Working path "/home/dan/personal/projects/foo" (directory)
[mbed] Creating new program "mbed_2_project" (git)
[mbed] Adding library "mbed" from "https://mbed.org/users/mbed_official/code/mbed/builds" at branch/tag "tip"
[mbed] Downloading library build "65be27845400" (might take a while)
[mbed] ERROR: Unknown Error: (128, 'Download failed!\nPlease try again later.')
```

After some digging this is because of a 404 error, but I don't know what it's trying to fetch:

`urllib.error.HTTPError: HTTP Error 404: Not Found`

```
mbed --version
1.10.2
```
(mbed installed via pip)
Ubuntu 18.04.3