Backport of the guestfs_aug_clear API from upstream development branch
(commit 66477d07e37ffe66c).

diff -ur libguestfs-1.2.2.orig/daemon/augeas.c libguestfs-1.2.2/daemon/augeas.c
--- libguestfs-1.2.2.orig/daemon/augeas.c	2010-04-12 19:03:41.000000000 +0100
+++ libguestfs-1.2.2/daemon/augeas.c	2010-04-14 10:03:10.307680521 +0100
@@ -210,6 +210,26 @@
 }
 
 int
+do_aug_clear (const char *path)
+{
+#ifdef HAVE_AUGEAS
+  int r;
+
+  NEED_AUG (-1);
+
+  r = aug_set (aug, path, NULL);
+  if (r == -1) {
+    reply_with_error ("Augeas clear failed");
+    return -1;
+  }
+
+  return 0;
+#else
+  NOT_AVAILABLE (-1);
+#endif
+}
+
+int
 do_aug_insert (const char *path, const char *label, int before)
 {
 #ifdef HAVE_AUGEAS
diff -ur libguestfs-1.2.2.orig/src/generator.ml libguestfs-1.2.2/src/generator.ml
--- libguestfs-1.2.2.orig/src/generator.ml	2010-04-12 19:05:28.000000000 +0100
+++ libguestfs-1.2.2/src/generator.ml	2010-04-14 10:03:10.312679892 +0100
@@ -1238,7 +1238,12 @@
    [], (* XXX Augeas code needs tests. *)
    "set Augeas path to value",
    "\
-Set the value associated with C<path> to C<value>.");
+Set the value associated with C<path> to C<val>.
+
+In the Augeas API, it is possible to clear a node by setting
+the value to NULL.  Due to an oversight in the libguestfs API
+you cannot do that with this call.  Instead you must use the
+C<guestfs_aug_clear> call.");
 
   ("aug_insert", (RErr, [String "augpath"; String "label"; Bool "before"]), 21, [Optional "augeas"],
    [], (* XXX Augeas code needs tests. *)
@@ -4400,6 +4405,13 @@
 You will get undefined results for other partition table
 types (see C<guestfs_part_get_parttype>).");
 
+  ("aug_clear", (RErr, [String "augpath"]), 239, [Optional "augeas"],
+   [], (* XXX Augeas code needs tests. *)
+   "clear Augeas path",
+   "\
+Set the value associated with C<path> to C<NULL>.  This
+is the same as the L<augtool(1)> C<clear> command.");
+
 ]
 
 let all_functions = non_daemon_functions @ daemon_functions
diff -ur libguestfs-1.2.2.orig/src/MAX_PROC_NR libguestfs-1.2.2/src/MAX_PROC_NR
--- libguestfs-1.2.2.orig/src/MAX_PROC_NR	2010-04-12 19:06:21.000000000 +0100
+++ libguestfs-1.2.2/src/MAX_PROC_NR	2010-04-14 10:03:43.885055262 +0100
@@ -1 +1 @@
-236
+239