How to install v1.9.0.beta1 version of discourse

Thanks for your comments, yes, I change this version(the commit id of v1.9.0.beta1) as follows:
version: 82ed51450e4b2912d3c650acd7a8332f90de9dc4
And I execute the command:
cd /var/discourse
./launcher rebuild app
But it failed, the upload file is fail log.fail log.txt (129.4 KB)