5847 libzfs_diff should check zfs_prop_get() return

*** 19,28 ****
--- 19,29 ----
   * CDDL HEADER END
   */
  
  /*
   * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
+  * Copyright 2015 Nexenta Systems, Inc. All rights reserved.
   */
  
  /*
   * zfs diff support
   */
*** 614,626 ****
                  (void) strncpy(di->ds, tosnap, tdslen);
                  di->ds[tdslen] = '\0';
  
                  zhp = zfs_open(hdl, di->ds, ZFS_TYPE_FILESYSTEM);
                  while (zhp != NULL) {
!                         (void) zfs_prop_get(zhp, ZFS_PROP_ORIGIN,
!                             origin, sizeof (origin), &src, NULL, 0, B_FALSE);
! 
                          if (strncmp(origin, fromsnap, fsnlen) == 0)
                                  break;
  
                          (void) zfs_close(zhp);
                          zhp = zfs_open(hdl, origin, ZFS_TYPE_FILESYSTEM);
--- 615,630 ----
                  (void) strncpy(di->ds, tosnap, tdslen);
                  di->ds[tdslen] = '\0';
  
                  zhp = zfs_open(hdl, di->ds, ZFS_TYPE_FILESYSTEM);
                  while (zhp != NULL) {
!                         if (zfs_prop_get(zhp, ZFS_PROP_ORIGIN, origin,
!                             sizeof (origin), &src, NULL, 0, B_FALSE) != 0) {
!                                 (void) zfs_close(zhp);
!                                 zhp = NULL;
!                                 break;
!                         }
                          if (strncmp(origin, fromsnap, fsnlen) == 0)
                                  break;
  
                          (void) zfs_close(zhp);
                          zhp = zfs_open(hdl, origin, ZFS_TYPE_FILESYSTEM);