serialization: 'fold-archive' notifies about directory processing completion.

* guix/serialization.scm (fold-archive): Call PROC with a
'directory-complete tag when done with a directory.
(restore-file): Handle it.
* guix/scripts/archive.scm (list-contents): Likewise.
* guix/scripts/challenge.scm (archive-contents): Likewise.
* tests/nar.scm ("write-file-tree + fold-archive"): Adjust accordingly.

1 files changed, 4 insertions, 2 deletions

diff --git a/tests/nar.scm b/tests/nar.scm
index aeff3d33304..b542ebd47c6 100644
--- a/tests/nar.scm
+++ b/tests/nar.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -218,8 +218,10 @@
   '(("R" directory #f)
     ("R/dir" directory #f)
     ("R/dir/exe" executable "1234")
+    ("R/dir" directory-complete #f)
     ("R/foo" regular "abcdefg")
-    ("R/lnk" symlink "foo"))
+    ("R/lnk" symlink "foo")
+    ("R" directory-complete #f))
 
   (let ()
     (define-values (port get-bytevector)