>> +(define (roll-back)
>> +  "Roll back to the previous profile."

> Please add a ‘profile’ parameter, as for the other functions.
>
> It should be possible to run:
> 
>   $ guix-package -p foo --roll-back

Should I add any profile-related sanity checks to 'roll-back'?

AFAICT, there are only manifest-specific ones (e.g., 'profile-manifest',
'manifest-packages').

Should 'roll-back' only work for 'guix-profile-*-link' and
'default-*-link'? If not, then we have a problem because 'profile-rx'
can't handle something like '42-custom-profile'. Is it possible to
create such a profile?

Nikita