Missing Debian/Ubuntu nightly packages

I am attempting to install clang-3.8 following instructions on this
page:

LLVM Debian/Ubuntu nightly packages
http://llvm.org/apt/

using this repository:

# 3.8
deb http://llvm.org/apt/trusty/ llvm-toolchain-trusty-3.8 main
deb-src http://llvm.org/apt/trusty/ llvm-toolchain-trusty-3.8 main

However these files do not exist:

http://llvm.org/apt/trusty/dists/

And of course it can be seen that there are also no files for 3.9 as
have been suggested on the main page.

I cannot get a response from Sylvestre Ledru who is listed as the page
contact so it has been suggested I try the broader community
represented by this mailing list.

My apologies if this is off topic here, any guidance would be
appreciated.

Andrew