Intermittent failure in /_webgl/conformance/renderbuffers/depth-renderbuffer-initialization.html

[jdm]

  ▶ Unexpected subtest result in /_webgl/conformance/renderbuffers/depth-renderbuffer-initialization.html:
  │ FAIL [expected PASS] WebGL test #38: should be 0,0,255,255\nat (32, 44) expected: 0,0,255,255 was 0,0,0,0
  │   → assert_true: should be 0,0,255,255
  │   → at (32, 44) expected: 0,0,255,255 was 0,0,0,0 expected true got false
  │ 
  │ reportTestResultsToHarness/<@http://web-platform.test:8000/_webgl/js/js-test-pre.js:123:24
  │ Test.prototype.step@http://web-platform.test:8000/resources/testharness.js:2001:25
  │ test@http://web-platform.test:8000/resources/testharness.js:548:30
  │ reportTestResultsToHarness@http://web-platform.test:8000/_webgl/js/js-test-pre.js:122:15
  │ testFailed@http://web-platform.test:8000/_webgl/js/js-test-pre.js:249:31
  │ checkCanvasRect/<@http://web-platform.test:8000/_webgl/js/webgl-test-utils.js:1269:19
  │ checkCanvasRectColor@http://web-platform.test:8000/_webgl/js/webgl-test-utils.js:1225:20
  │ checkCanvasRect@http://web-platform.test:8000/_webgl/js/webgl-test-utils.js:1257:23
  │ runTest@http://web-platform.test:8000/_webgl/conformance/renderbuffers/depth-renderbuffer-initialization.html:138:9
  └ @http://web-platform.test:8000/_webgl/conformance/renderbuffers/depth-renderbuffer-initialization.html:62:16

I suspect this is yet another case of error messages including pixel data from uninitializes graphics memory.