This mitigates <https://bugs.gnu.org/27284>.
* guix/self.scm: New file.
* Makefile.am (MODULES): Add it.
* build-aux/build-self.scm (libgcrypt, zlib, gzip, bzip2, xz)
(false-if-wrong-guile, package-for-current-guile, guile-json)
(guile-ssh, guile-git, guile-bytestructures): Remove.
(build): Rewrite to simply delegate to 'compiled-guix'.
* gnu/packages.scm (%distro-root-directory): Rewrite to try different
directories.
* guix/discovery.scm (guix): Export 'scheme-files'.
* guix/scripts/pull.scm (build-and-install): Split into...
(install-latest): ... this. New procedure. And...
(build-and-install): ... this, which now takes a monadic value argument.
(indirect-root-added): Remove.
(guix-pull): Call 'add-indirect-root'. Call 'build-from-source' and
pass the result to 'build-and-install'.