I'm assuming this doesn't have any meaningful effect, and it seems to reduce
the number of readlink calls by a lot.

* build-aux/build-self.scm (build-program): Set
%file-port-name-canonicalization to #f.
(build): Ditto.
* build-aux/compile-as-derivation.scm: Ditto.

Change-Id: If43415c46c3911e84c76d1a9828b9c417a140a1b

To avoid one character per syscall output from within the build procedure.

* build-aux/compile-as-derivation.scm: Buffer the current-error-port.

Change-Id: I7725ef0cb1f3ad4e9f5fdd284734f376fd57b253

* build-aux/compile-as-derivation.scm: Set not only %load-path but also
%load-compiled-path.  This can avoid problems where a stale .go is
loaded.

* guix/scripts/pull.scm (%pull-version): New variable.
(build-from-source): Pass #:pull-version to BUILD.
(whole-package-for-legacy, derivation->manifest-entry): New procedure.
(build-and-install): Rewrite in terms of 'build-and-use-profile'.
* guix/scripts/system.scm (maybe-suggest-running-guix-pull)[latest]:
Switch to "/current".
* scripts/guix.in (augment-load-paths!): Remove use of
~/.config/guix/latest.
* build-aux/compile-as-derivation.scm: Replace "/guix/latest/" with
"/current/share/guile/site/X.Y"
* guix/scripts.scm (warn-about-old-distro)[age]: Check "/current"
instead of "/latest".
* doc/guix.texi (Invoking guix pull): Document it.
* doc/contributing.texi (Running Guix Before It Is Installed): Remove
footnote about abusing ~/.config/guix/latest.

* guix/self.scm (guix-command): New procedure.
(compiled-guix): Add #:pull-version parameter.
[command, package]: New variables.
Honor PULL-VERSION.
(guix-derivation): Add #:pull-version and pass it to 'compiled-guix'.
* build-aux/build-self.scm (build-program): Add #:pull-version
parameter.  Pass it to 'guix-derivation'.
(build): Add #:pull-version and pass it to 'build-program'.
* build-aux/compile-as-derivation.scm: Pass #:pull-version to BUILD.

* build-aux/compile-as-derivation.scm: New file.
* Makefile.am (as-derivation): New target.
(EXTRA_DIST): Add compile-as-derivation.scm.