activation: Aways pass '-d HOME' to 'useradd'.

Fixes <https://bugs.gnu.org/33422>.
Reported by fps.

* gnu/build/activation.scm (add-user): Always pass "-d HOME" when HOME
is true.  Pass "--create-home" only when HOME, CREATE-HOME?, and SYSTEM?
are true.
(activate-users+groups): Pass #:create-home? create-home? to
'ensure-user'.
* gnu/tests/base.scm (run-basic-test)["accounts"]: Test 'passwd:dir' as
well.

gnu/build/activation.scm

@@ -148,11 +148,15 @@ properties.  Return #t on success."
                           `("-G" ,(string-join supplementary-groups ","))
                           '())
                     ,@(if comment `("-c" ,comment) '())
-                    ,@(if (and home create-home?)
-                          (if (file-exists? home)
-                              `("-d" ,home)     ; avoid warning from 'useradd'
-                              `("-d" ,home "--create-home"))
+                    ,@(if home `("-d" ,home) '())
+
+                    ;; Home directories of non-system accounts are created by
+                    ;; 'activate-user-home'.
+                    ,@(if (and home create-home? system?
+                               (not (file-exists? home)))
+                          '("--create-home")
                           '())
+
                     ,@(if shell `("-s" ,shell) '())
                     ,@(if password `("-p" ,password) '())
                     ,@(if system? '("--system") '())
@@ -229,10 +233,7 @@ numeric gid or #f."
                      #:supplementary-groups supplementary-groups
                      #:comment comment
                      #:home home
-
-                     ;; Home directories of non-system accounts are created by
-                     ;; 'activate-user-home'.
-                     #:create-home? (and create-home? system?)
+                     #:create-home? create-home?
 
                      #:shell shell
                      #:password password)

gnu/tests/base.scm

@@ -154,10 +154,15 @@ info --version")
                                                  (#f (reverse result))
                                                  (x  (loop (cons x result))))))
                                           marionette)))
-              (lset= string=?
-                     (map passwd:name users)
+              (lset= equal?
+                     (map (lambda (user)
+                            (list (passwd:name user)
+                                  (passwd:dir user)))
+                          users)
                      (list
-                      #$@(map user-account-name
+                      #$@(map (lambda (account)
+                                `(list ,(user-account-name account)
+                                       ,(user-account-home-directory account)))
                               (operating-system-user-accounts os))))))
 
           (test-assert "shepherd services"