Try to fix 5.2 branch

[gforcada]

Since a few builds one of the jenkins jobs targetting 5.2 branch is failing, my guess is that plone/plone.indexer#6 was the problem as it was merged although the 5.2 jenkins job pull request failed, was there a good reason to ignore it? @jensens

Let's see if, indeed, removing plone.indexer fixes the problem.

[jensens]

At time of merging it was green IIRC. Also, there were other PRs merged together with plone.indexer.

I think a side effect came in with plone.restapi, but no idea why it did not hit the PR...
here https://jenkins.plone.org/job/pull-request-5.2/962/testReport/plone.restapi.tests.test_search/TestSearchFunctional/test_full_metadata_retrieval/

The problem: Before exclude_from_nav metadata was accidentally acquired. Now it is not and the returned value is None instead of the previously acquired False.

Question here is,

• do we want to accept the new behavior, which is telling us there was no explicit value set?
• or do we want to register an indexer returning false on items w/o the attribute exclude_from_nav?

[jensens]

should be solved with plone/plone.restapi#580