bug#22626: Postgres service fails on adding user

[Christopher Allan Webber]

Heya all... guix system config attached.  I tried doing a guix system
reconfigure and it failboat'ed.  Here's what happened:

  adding user 'postgres'...
  useradd: group 'postgres' does not exist
  Backtrace:
  In ice-9/boot-9.scm:
    63: 19 [call-with-prompt prompt0 ...]
  In ice-9/eval.scm:
   432: 18 [eval # #]
  In ice-9/boot-9.scm:
  2401: 17 [save-module-excursion #<procedure 28dc940 at 
ice-9/boot-9.scm:4045:3 ()>]
  4050: 16 [#<procedure 28dc940 at ice-9/boot-9.scm:4045:3 ()>]
  1724: 15 [%start-stack load-stack ...]
  1729: 14 [#<procedure 28f3ea0 ()>]
  In unknown file:
     ?: 13 [primitive-load 
"/gnu/store/24mbii9wjlyzfzsqwfmcvz6vz2fv5n6g-guix-0.9.0.c3f29bc/bin/.guix-real"]
  In guix/ui.scm:
  1177: 12 [run-guix-command system "reconfigure" "guix-config.scm"]
  In ice-9/boot-9.scm:
   157: 11 [catch srfi-34 #<procedure 4fb2020 at guix/ui.scm:413:2 ()> ...]
   157: 10 [catch system-error ...]
  In guix/scripts/system.scm:
   701: 9 [process-action reconfigure ("guix-config.scm") ...]
  In guix/store.scm:
  1061: 8 [run-with-store # ...]
  In guix/scripts/system.scm:
   520: 7 [#<procedure 91f6f80 at guix/scripts/system.scm:520:13 (state)> #]
   302: 6 [#<procedure 9661740 at guix/scripts/system.scm:286:2 (state)> #]
  In unknown file:
     ?: 5 [primitive-load 
"/gnu/store/fnanaa7xalxa9h3yh1hpj3m5zgm9wasp-activate"]
  In ice-9/eval.scm:
   432: 4 [eval # ()]
  In ice-9/boot-9.scm:
   768: 3 [for-each #<procedure primitive-load (_)> #]
  In unknown file:
     ?: 2 [primitive-load 
"/gnu/store/hz2hnin6c12afvsyqxv0vs2rndxl9vpg-activate-servic
  e"]
  In ice-9/eval.scm:
   411: 1 [eval # ()]
  In unknown file:
     ?: 0 [getpw "postgres"]
  
  ERROR: In procedure getpw:
  ERROR: In procedure getpw: entry not found

Config attached.  Thanx!
 - cwebb

guix-config.scm
Description: Binary data