Greylist moving-shards-with-arangosearch-view-cluster. (#7273)

* Greylist moving-shards-with-arangosearch-view-cluster.

* Add documentation for greylisted tests.

README_maintainers.md

@@ -209,6 +209,14 @@ These tests are ran using the jasmine framework instead of jsunity.
 --------
 These tests produce a certain thread on infrastructure or the test system, and therefore should only be executed once per day.
 
+-grey
+-----
+These tests are currently listed as "grey", which means that they are
+known to be unstable or broken. These tests will not be executed by the
+testing framework if the option `--skipGrey` is given. See
+`tests/Greylist.txt` for up-to-date information about greylisted tests.
+Please help to keep this file up to date.
+
 Test frameworks used
 ====================
 There are several major places where unittests live: 

tests/Greylist.txt

@@ -0,0 +1,11 @@
+# Greylist information
+
+In this file we collect information about which tests are currently
+greylisted. Please add a reason and date, and possibly links to issues
+or PRs.
+
+ - `./tests/js/server/resilience/moving-shards-with-arangosearch-view-cluster.js`
+   as of now this test has frequent failures. The issue seems to be that
+   the MoveShard operation from one leader to a different one does not
+   reliably drop the old leader as a follower from the Plan in the end.
+   See https://github.com/arangodb/release-3.4/issues/125