Compile guix from git?

[韋嘉誠]

How do people compile guix directly from git source? I've been
searching around in HACKING and manual.html#Contributing and other
places, the internet in general, and haven't been able to find any
instructions.

It ought to be:

1. Get dependencies manually or with 'guix environment guix'.
2. aclocal
3. automake, maybe automake -a
4. autoconf
5. configure --sharedstatedir=/var --with-libgcrypt-prefix=wherever
6. make

But #3 fails. nix/config.h.in is missing, maybe other things too but
that's where it halts.

What I do now to make it work is I insert:

1.1. tar axf --strip-component=1 /path/to/guix-0.8.2.tar.gz
1.2. git checkout HEAD .
1.3. git clean -fd

Seems to be working, but there must be something everyone else is
doing that I missed in a document somewhere. Or maybe everyone is
working in checkouts made at some point when that file existed?