TypeError: copy() got an unexpected keyword argument 'follow_symlinks'
I googled and found that shutil.copy() with follow_symlinks argument should be python3 only. This error messages seems that it was calling python2, hence didn't know what follow_symlinks was. However, I looked at the /usr/lib/live/build/chroot-hooks. It calls /usr/bin/python3 as its shell interpreter, and my /usr/bin/python3 points to /usr/bin/python3.2mu, which was installed by ubuntu.
Is it a bug of live-build 4.0 alpha? I'll try with 3.0.5 later.