bug#29287: tramp-test25-file-selinux fails

[Glenn Morris]

Package: emacs
Version: 26.0.90

tramp-test25-file-selinux fails on RHEL7.4 with SELinux enabled.
Reporting as requested in the comment in the source file. :)

Test tramp-test25-file-selinux backtrace:
  signal(ert-test-failed (((should-not (equal (file-selinux-context tm
  ert-fail(((should-not (equal (file-selinux-context tmp-name1) (file-
  (if (not (unwind-protect (setq value-4340 (apply fn-4338 args-4339))
  (let (form-description-4342) (if (not (unwind-protect (setq value-43
  (let ((value-4340 'ert-form-evaluation-aborted-4341)) (let (form-des
  (let* ((fn-4338 (function equal)) (args-4339 (condition-case err (le
  (progn (write-region "foo" nil tmp-name1) (let* ((fn-4318 (function 
  (unwind-protect (progn (write-region "foo" nil tmp-name1) (let* ((fn
  (let ((tmp-name1 (tramp--test-make-temp-name nil quoted)) (tmp-name2
  (let (quoted) (let ((tmp-name1 (tramp--test-make-temp-name nil quote
  (closure (t) nil (let* ((fn-4308 (function tramp--test-enabled)) (ar
  ert--run-test-internal(#s(ert--test-execution-info :test #s(ert-test
  ert-run-test(#s(ert-test :name tramp-test25-file-selinux :documentat
  ert-run-or-rerun-test(#s(ert--stats :selector (not (tag :expensive-t
  ert-run-tests((not (tag :expensive-test)) #f(compiled-function (even
  ert-run-tests-batch((not (tag :expensive-test)))
  ert-run-tests-batch-and-exit((not (tag :expensive-test)))
  eval((ert-run-tests-batch-and-exit '(not (tag :expensive-test))))
  command-line-1(("-L" ":." "-l" "ert" "-l" "lisp/net/tramp-tests.el" 
  command-line()
  normal-top-level()
Test tramp-test25-file-selinux condition:
    (ert-test-failed
     ((should-not
       (equal
        (file-selinux-context tmp-name1)
        (file-selinux-context tmp-name2)))
      :form
      (equal
       ("unconfined_u" "object_r" "user_tmp_t" "s0")
       ("unconfined_u" "object_r" "user_tmp_t" "s0"))
      :value t :explanation nil))
   FAILED  29/41  tramp-test25-file-selinux