Fix repair_key and add test case

test/expected/repair_key.out

@@ -0,0 +1,17 @@
+\set ECHO none
+ repair_key 
+------------
+
+(1 row)
+
+ remove_provenance 
+-------------------
+
+(1 row)
+
+ ground | round 
+--------+-------
+ dry    | 0.550
+ wet    | 0.450
+(2 rows)
+

test/sql/repair_key.sql

@@ -0,0 +1,24 @@
+\set ECHO none
+SET search_path TO provsql_test,provsql;
+
+CREATE TABLE weather_conditions (dummy VARCHAR, weather VARCHAR,
+                ground VARCHAR, p FLOAT);
+INSERT INTO weather_conditions VALUES ('dummy',    'rain', 'wet', 0.35);
+INSERT INTO weather_conditions VALUES ('dummy',    'rain', 'dry', 0.05);
+INSERT INTO weather_conditions VALUES ('dummy', 'no rain', 'wet', 0.1);
+INSERT INTO weather_conditions VALUES ('dummy', 'no rain', 'dry', 0.5);
+
+SELECT repair_key('weather_conditions','dummy');
+DO $$ BEGIN
+  PERFORM set_prob(provenance(), p) FROM weather_conditions;
+END $$;
+
+CREATE TABLE result_repair_key AS
+  SELECT *, probability_evaluate(provenance()) prob FROM (
+    SELECT ground FROM weather_conditions GROUP BY ground) t;
+
+SELECT remove_provenance('result_repair_key');
+SELECT ground, ROUND(prob::numeric, 3) FROM result_repair_key;
+
+DROP TABLE result_repair_key;
+DROP TABLE weather_conditions;