autopkgtest fails in focal

https://objectstorage.prodstack4-5.canonical.com/v1/AUTH_77e2ada1e7a84929a74ba3b87153c0ac/autopkgtest-focal/focal/amd64/p/postgresql-multicorn/20200907_203129_ee45b@/log.gz

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test multicorn_planner_test ... FAILED 55 ms
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**** regression.diffs ****
diff -U3 /tmp/autopkgtest.6VeiV5/build.Rwe/src/test-3.8/expected/multicorn_planner_test.out /tmp/autopkgtest.6VeiV5/build.Rwe/src/results/multicorn_planner_test.out
--- /tmp/autopkgtest.6VeiV5/build.Rwe/src/test-3.8/expected/multicorn_planner_test.out 2019-10-18 08:37:04.000000000 +0000
+++ /tmp/autopkgtest.6VeiV5/build.Rwe/src/results/multicorn_planner_test.out 2020-09-07 20:31:17.648523078 +0000
@@ -23,7 +23,7 @@
 explain select * from testmulticorn m1 inner join testmulticorn m2 on m1.test1 = m2.test1;
                                      QUERY PLAN
 -------------------------------------------------------------------------------------
- Nested Loop (cost=20.00..806.05 rows=2 width=128)
+ Nested Loop (cost=20.00..806.05 rows=20 width=128)
    Join Filter: ((m1.test1)::text = (m2.test1)::text)
    -> Foreign Scan on testmulticorn m1 (cost=10.00..400.00 rows=20 width=20)
    -> Materialize (cost=10.00..400.10 rows=20 width=20)
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