Subject: how gcc-toolchain can depends a package who doesn't exists?

From: bbb ee <[email-masked]>
Date: Tue, 15 Nov 2022 00:53:32 +0100

in version c81457a5883ea43950eb2ecdcbb58a5b144bcd11 of guix, gcc-toolchain
depends gcc:
```
$ DEFAULT_CHANNELS=/tmp/default_channels.scm
$ echo "%default-channels" > $DEFAULT_CHANNELS
# I force guix to use only %default-channels here
$ guix time-machine --commit=c81457a5883ea43950eb2ecdcbb58a5b144bcd11  -C
$DEFAULT_CHANNELS -- search gcc-toolchain
guile: warning: failed to install locale
name: gcc-toolchain
version: 9.3.0
outputs: out debug static
systems: x86_64-linux i686-linux
dependencies: [email-masked] [email-masked] [email-masked] ld-wrapper@0
```

However, I can't find gcc package in this version of guix
```
$ guix time-machine --commit=c81457a5883ea43950eb2ecdcbb58a5b144bcd11  -C
$DEFAULT_CHANNELS -- search gcc
# no found gcc

# guix install failure message confirm that gcc doesn't exist in commit
c81457
$ guix time-machine --commit=c81457a5883ea43950eb2ecdcbb58a5b144bcd11 -C
$DEFAULT_CHANNELS -- install gcc -p ~/opt/python-dev_3_7
guile: warning: failed to install locale
guix install: error: gcc: unknown package
```

in commit c81457, how gcc-toolchain can depends a package who doesn't
exists?