Compiling ghcjs

Hi,

I hope this is the correct list to ask this question.

I am trying to compile the ghcjs compiler. I am on ubuntu 12.04 and have
ghc-7.4.1 installed (via apt-get).

I am following the instruction I found here: https://github.com/ghcjs/ghcjs

The first trouble comes with "git pull ghcjs". I get:

remote: Counting objects: 42, done.
remote: Compressing objects: 100% (9/9), done.
remote: Total 26 (delta 22), reused 21 (delta 17)
Unpacking objects: 100% (26/26), done.
>From github.com:ghcjs/packages-Cabal
 * [new branch]      encoding   -> ghcjs/encoding
 * [new branch]      ghc-7.2    -> ghcjs/ghc-7.2
 * [new branch]      ghc-7.4    -> ghcjs/ghc-7.4
 * [new branch]      master     -> ghcjs/master
You asked to pull from the remote 'ghcjs', but did not specify
a branch. Because this is not the default configured remote
for your current branch, you must specify a branch on the command line.

So I am doing:

git pull ghcjs ghc-7.4

Then "git branch ghc-7.4 ghcjs/ghc-7.4" gives me:

fatal: A branch named 'ghc-7.4' already exists.

And finaly "perl boot" fails with:

Error: libraries/extensible-exceptions/LICENSE doesn't exist.
Maybe you haven't done './sync-all get'? at boot line 74, 
line 57.

What can I do?
Thanks!
Nathan