Improve reproducibility of test runs.

test/mjsunit/mjsunit.status

 # Copyright 2012 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 75 matching lines @@
   'json-recursive': [PASS, ['mode == debug', PASS, FAIL]],
 
   ##############################################################################
   # Skip long running tests that time out in debug mode.
   'generated-transition-stub': [PASS, ['mode == debug', SKIP]],
 
   ##############################################################################
   # This test sets the umask on a per-process basis and hence cannot be
   # used in multi-threaded runs.
   # On android there is no /tmp directory.
-  'd8-os': [PASS, ['isolates or arch == android_arm or arch == android_arm64 or arch == android_ia32', SKIP]],
+  # Currently d8-os generates a temporary directory name using Math.random(), so
+  # we cannot run several variants of d8-os simultaneously, since all of them
+  # get the same random seed and would generate the same directory name. Besides
+  # that, it doesn't make sense to run several variants of d8-os anyways.
+  'd8-os': [PASS, NO_VARIANTS, ['isolates or arch == android_arm or arch == android_arm64 or arch == android_ia32', SKIP]],
   'tools/tickprocessor': [PASS, ['arch == android_arm or arch == android_arm64 or arch == android_ia32', SKIP]],
 
   ##############################################################################
   # Long running test that reproduces memory leak and should be run manually.
   'regress/regress-2073': [SKIP],
 
   ##############################################################################
   # Tests verifying CHECK and ASSERT.
   'verify-check-false': [FAIL, NO_VARIANTS],
   'verify-assert-false': [NO_VARIANTS, ['mode == release', PASS], ['mode == debug', FAIL]],
@@ skipping 274 matching lines @@
   'never-optimize': [SKIP],
   'regress/regress-2185-2': [SKIP],
   'harmony/object-observe': [SKIP],
   'readonly': [SKIP],
   'array-feedback': [SKIP],
 
   # Deopt every n garbage collections collides with deopt every n times.
   'regress/regress-2653': [SKIP],
 }],  # 'deopt_fuzzer == True'
 ]