[Explain] test_bidirectional_join failing,covers not present in explain output

Test which is failing:

./testrunner -i /tmp/n1ql_set1.ini get-cbcollect-info=True,gsi_type=forestdb,primary_indx_type=VIEW,doc-per-day=6,standard_buckets=1,nodes_init=3 -t tuqquery.tuq_join.JoinTests.test_bidirectional_join

What the test does?

CREATE INDEX ix1 ON default(docid,name)

CREATE INDEX ix2 ON default(docid,name) where type = "wdoc"

CREATE INDEX ix3 ON default(altid, name, DISTINCT ARRAY p FOR p IN phones END)

INSERT into %s (key , value) VALUES ("%s", %s)' % ("default", "w001", {"type":"wdoc", "docid":"x001","name":"wdoc","phones":["123-456-7890","123-456-7891"],"altid":"x001"})

INSERT into %s (key , value) VALUES ("%s", %s)' % ("default", "pdoc1", {"type":"pdoc", "docid":"x001","name":"pdoc","phones":["123-456-7890","123-456-7891"],"altid":"x001"})

INSERT into %s (key , value) VALUES ("%s", %s)' % ("default", "pdoc2", {"type":"pdoc", "docid":"w001","name":"pdoc","phones":["123-456-7890","123-456-7891"],"altid":"w001"})

explain SELECT meta(b1).id b1id FROM default b1 JOIN default b2 ON KEY b2.docid FOR b1 WHERE meta(b1).id > ""'

Assertion Failure seen:

======================================================================

FAIL: test_bidirectional_join (tuqquery.tuq_join.JoinTests)

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Traceback (most recent call last):

  File "pytests/tuqquery/tuq_join.py", line 132, in test_bidirectional_join

    self.assertTrue("covers" in str(actual_result))

AssertionError: False is not true

Above test was suggested by query dev as part of another bug fix on index joins.

This is a regression from build 1984.