`./xtool setup` failed with no explicit error message.

the command and output is as below, I am running it on an ubuntu 14.04 machine.

$ ./xtool setup Setting up the build environment...

git submodule init / update... Cloning into 'third_party/glm'... remote: Counting objects: 46915, done. remote: Compressing objects: 100% (7/7), done. remote: Total 46915 (delta 2), reused 4 (delta 1), pack-reused 46907 Receiving objects: 100% (46915/46915), 62.37 MiB | 4.36 MiB/s, done. error: RPC failed; result=56, HTTP code = 200 Resolving deltas: 100% (34376/34376), done. Clone of 'https://github.com/g-truc/glm.git' into submodule path 'third_party/glm' failed Traceback (most recent call last): File "./xtool", line 1821, in sys.exit(main()) File "./xtool", line 126, in main return_code = command.execute(args, pass_args, os.getcwd()) File "./xtool", line 662, in execute git_submodule_update() File "./xtool", line 474, in git_submodule_update '--recursive', File "./xtool", line 324, in shell_call subprocess.check_call(command, shell=False, stdout=stdout_file) File "/usr/lib/python2.7/subprocess.py", line 540, in check_call raise CalledProcessError(retcode, cmd) subprocess.CalledProcessError: Command '['git', 'submodule', 'update', '--init', '--recursive']' returned non-zero exit status 1

google / xrtl