Remove comment obsoleted by 11c2d6f.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/1604497.1680637072%40sss.pgh.pa.us

Author: macdice

src/backend/optimizer/path/joinpath.c

@@ -2190,9 +2190,8 @@ hash_inner_and_outer(PlannerInfo *root,
 		 * If the joinrel is parallel-safe, we may be able to consider a
 		 * partial hash join.  However, we can't handle JOIN_UNIQUE_OUTER,
 		 * because the outer path will be partial, and therefore we won't be
-		 * able to properly guarantee uniqueness.  Similarly, we can't handle
-		 * JOIN_FULL and JOIN_RIGHT, because they can produce false null
-		 * extended rows.  Also, the resulting path must not be parameterized.
+		 * able to properly guarantee uniqueness.  Also, the resulting path
+		 * must not be parameterized.
 		 */
 		if (joinrel->consider_parallel &&
 			save_jointype != JOIN_UNIQUE_OUTER &&