Controversy: be defensive against negative ups/downs (bad data)

r2/r2/lib/db/_sorts.pyx

@@ -57,7 +57,7 @@ cpdef double _hot(long ups, long downs, double date):
 
 cpdef double controversy(long ups, long downs):
     """The controversy sort."""
-    if downs == 0 or ups == 0:
+    if downs <= 0 or ups <= 0:
         return 0
 
     magnitude = ups + downs

sql/functions.sql

@@ -29,7 +29,7 @@ create or replace function score(ups integer, downs integer) returns integer as
 $$ language sql immutable;
 
 create or replace function controversy(ups integer, downs integer) returns float as $$
-    select CASE WHEN $1 = 0 or $2 = 0 THEN 0
+    select CASE WHEN $1 <= 0 or $2 <= 0 THEN 0
                 WHEN $1 > $2 THEN power($1 + $2, cast($2 as float) / $1)
                 ELSE power($1 + $2, cast($1 as float) / $2)
            END;