bug#35601: First 'guix pull' does not display 'hash guix' hint

[Diego Nicola Barbato]

Hi Guix,

Congratulations on 1.0.0!

I took the opportunity to revisit bug #33647 [0] and verify that commits
3bbd691 and d1d7283 have the desired effect.  Unfortunately they do
not: The first time a user runs guix pull on a freshly installed Guix
System no hint about running 'hash guix' is displayed even though it is
precisely when the hint was supposed to be displayed.

To reproduce simply run (after installing Guix System using the 1.0.0
installer) 'guix --version', which will yield 'guix (GNU Guix) 1.0.0',
then 'guix pull', which will display no hint about running 'hash guix',
then 'guix --version' again, which will return 'guix (GNU Guix) 1.0.0'
again, and finally 'hash guix' followed by 'guix --version', which now
will yield 'guix (GNU Guix) 1234somecommithash123456789abcdefghijklm'.

Regardless of the hint I still believe it is unfortunate that running
'guix pull && guix system reconfigure /etc/config.scm' for the first
time will rather counterintuitively downgrade the system instead of
upgrading it.

Regards,

Diego

[0]: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=33647