bug#38529: Make --ad-hoc the default for guix environment proposed deprecation mechanism

[Bengt Richter]

Forgot to add:
┌──────────────────────────────────────────────────────────────────────────┐
│          guile -c '(use-modules (ice-9 session))(apropos "env")          │
├──────────────────────────────────────────────────────────────────────────┤
│ (guile): getenv  #<procedure getenv (_)>                                 │
│ (guile): environ #<procedure environ (#:optional _)>                     │
│ (guile): setenv #<procedure setenv (name value)>                         │
│ (guile): interaction-environment #<procedure interaction-environment ()> │
│ (guile): putenv #<procedure putenv (_)>                                  │
│ (guile): unsetenv #<procedure unsetenv (name)>                           │
└──────────────────────────────────────────────────────────────────────────┘

BTW, it would be really handy to be able to type
   guile -apropos rest of line as regex
for the effect of
   ,a rest of line as regex
in the guile repl
-- 
Regards,
Bengt Richter