Jest JUnit output seems to be invalid

[spalger]

https://kibana-ci.elastic.co/job/elastic+kibana+master/312/JOB=kibana-intake,node=immutable/console

00:28:37.054 Test Suites: 1 failed, 1 skipped, 555 passed, 556 of 557 total
00:28:37.054 Tests:       1 skipped, 3753 passed, 3754 total
00:28:37.055 Snapshots:   1203 passed, 1203 total
00:28:37.055 Time:        271.97s
00:28:37.056 �[2mRan all test suites�[22m�[2m.�[22m
00:28:37.299 Fatal error: jest exited with code 1�
00:28:44.781 (node:6667) UnhandledPromiseRejectionWarning: TypeError: testFile.testcase is not iterable
00:28:44.781     at testFiles.reduce (/var/lib/jenkins/workspace/elastic+kibana+master/JOB/kibana-intake/node/immutable/kibana/src/dev/failed_tests/report.js:54:37)
00:28:44.792     at Array.reduce (<anonymous>)
00:28:44.792     at testSuite (/var/lib/jenkins/workspace/elastic+kibana+master/JOB/kibana-intake/node/immutable/kibana/src/dev/failed_tests/report.js:53:30)
00:28:44.793     at Transform.transform [as _transform] (/var/lib/jenkins/workspace/elastic+kibana+master/JOB/kibana-intake/node/immutable/kibana/src/legacy/utils/streams/map_stream.js:29:25)
00:28:44.793     at Transform._read (_stream_transform.js:190:10)
00:28:44.796     at Transform._write (_stream_transform.js:178:12)
00:28:44.796     at doWrite (_stream_writable.js:410:12)
00:28:44.796     at writeOrBuffer (_stream_writable.js:394:5)
00:28:44.796     at Transform.Writable.write (_stream_writable.js:294:11)
00:28:44.797     at Transform.ondata (_stream_readable.js:667:20)
00:28:44.797 (node:6667) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
00:28:44.797 (node:6667) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
00:28:45.501 runbld>>> <<<<<<<<<<<< SCRIPT EXECUTION END <<<<<<<<<<<<
00:28:45.501 runbld>>> DURATION: 1691914ms
00:28:45.501 runbld>>> STDOUT: 171641 bytes
00:28:45.501 runbld>>> STDERR: 102451 bytes
00:28:45.502 runbld>>> WRAPPED PROCESS: FAILURE (1)
00:28:45.502 runbld>>> Adding test report.
00:28:45.504 runbld>>> Searching for junit test output files with the pattern: TEST-.*\.xml$ in: /var/lib/jenkins/workspace/elastic+kibana+master/JOB/kibana-intake/node/immutable/kibana
00:29:01.837 runbld>>> Found 2 test output files
00:29:04.849 runbld>>> Test output logs contained: Errors: 0 Failures: 0 Tests: 5213 Skipped: 6
00:29:05.104 runbld>>> Storing result
00:29:05.104 runbld>>> FAILURES: 0
00:29:05.443 runbld>>> Store result: updated {:total 2, :successful 2, :failed 0} 2
00:29:05.444 runbld>>> BUILD: https://c150076387b5421f9154dfbf536e5c60.us-west1.gcp.cloud.es.io:9243/build-1531848254847/t/20190307063727-CC76656E
00:29:05.793 runbld>>> NO MAIL GENERATED
00:29:11.173 Build step 'Execute shell' marked build as failure

[elasticmachine]

Pinging @elastic/kibana-test-triage