system: Rename and move %base-packages-disk-utilities.

Rationale: It is only used in INSTALLATION-OS and doesn't make sense to be
used in another context, given that file systems now automatically pull their
dependencies since commit 45eac6cdf5 (services:
Add file system utilities to profile).

* gnu/system.scm (%base-packages-disk-utilities): Deprecate and rename to...
* gnu/system/install.scm (%installer-disk-utilities): ... this.
(installation-os) [packages]: Adjust accordingly.

gnu/system.scm

@@ -38,6 +38,7 @@ (define-module (gnu system)
   #:use-module (guix gexp)
   #:use-module (guix records)
   #:use-module (guix packages)
+  #:use-module (guix deprecation)
   #:use-module (guix derivations)
   #:use-module (guix profiles)
   #:use-module ((guix utils) #:select (substitute-keyword-arguments))
@@ -49,9 +50,6 @@ (define-module (gnu system)
   #:use-module (gnu packages bash)
   #:use-module (gnu packages compression)
   #:use-module (gnu packages cross-base)
-  #:use-module (gnu packages cryptsetup)
-  #:use-module (gnu packages disk)
-  #:use-module (gnu packages file-systems)
   #:use-module (gnu packages firmware)
   #:use-module (gnu packages gawk)
   #:use-module (gnu packages guile)
@@ -896,20 +894,7 @@ (define %base-packages-networking
         ;; many people are familiar with, so keep it around.
         iw wireless-tools))
 
-(define %base-packages-disk-utilities
+(define-deprecated %base-packages-disk-utilities #f '())
-  ;; A well-rounded set of packages for interacting with disks,
-  ;; partitions and filesystems, included with the Guix installation
-  ;; image.
-  (list parted gptfdisk ddrescue
-        ;; We used to provide fdisk from GNU fdisk, but as of version 2.0.0a
-        ;; it pulls Guile 1.8, which takes unreasonable space; furthermore
-        ;; util-linux's fdisk is already available, in %base-packages-linux.
-        cryptsetup mdadm
-        dosfstools
-        btrfs-progs
-        f2fs-tools
-        jfsutils
-        xfsprogs))
 
 (define %base-packages
   ;; Default set of packages globally visible.  It should include anything

gnu/system/install.scm

@@ -48,6 +48,9 @@ (define-module (gnu system install)
   #:use-module (gnu packages bootloaders)
   #:use-module (gnu packages certs)
   #:use-module (gnu packages compression)
+  #:use-module (gnu packages cryptsetup)
+  #:use-module (gnu packages disk)
+  #:use-module (gnu packages file-systems)
   #:use-module (gnu packages fonts)
   #:use-module (gnu packages fontutils)
   #:use-module (gnu packages guile)
@@ -458,6 +461,20 @@ (define %issue
 \x1b[1;33mUse Alt-F2 for documentation.\x1b[0m
 ")
 
+(define %installer-disk-utilities
+  ;; A well-rounded set of packages for interacting with disks, partitions and
+  ;; file systems, included with the Guix installation image.
+  (list parted gptfdisk ddrescue
+        ;; We used to provide fdisk from GNU fdisk, but as of version 2.0.0a
+        ;; it pulls Guile 1.8, which takes unreasonable space; furthermore
+        ;; util-linux's fdisk is already available, in %base-packages-linux.
+        cryptsetup mdadm
+        dosfstools
+        btrfs-progs
+        f2fs-tools
+        jfsutils
+        xfsprogs))
+
 (define installation-os
   ;; The operating system used on installation images for USB sticks etc.
   (operating-system
@@ -530,7 +547,7 @@ (define installation-os
                       font-dejavu font-gnu-unifont
                       grub          ; mostly so xrefs to its manual work
                       nss-certs)    ; To access HTTPS, use git, etc.
-                %base-packages-disk-utilities
+                %installer-disk-utilities
                 %base-packages))))
 
 (define* (os-with-u-boot os board #:key (bootloader-target "/dev/mmcblk0")