Remove incorrect version check in binary upgrade dumps

We must support older than 80300 in dumping pg_type Oid's in order
to support upgrades from 4.3. Remove bogus check inherited from
upstream PostgreSQL where 8.3 is the earliest version supported by
pg_upgrade. Replace with a check for 8.2 as the base version in
the main binary upgrade dump function and explain the difference
to upstream.

src/bin/pg_dump/binary_upgrade.c

@@ -870,10 +870,6 @@ preassign_type_oids_by_rel_oid(PGconn *conn, Archive *fout, Archive *AH, Oid pg_
 	Oid			pg_type_oid;
 	bool		columnstore;
 
-	/* we only support old >= 8.3 for binary upgrades */
-	if (fout->remoteVersion >= 80300)
-		return;
-
 	upgrade_query = createPQExpBuffer();
 	upgrade_buffer = createPQExpBuffer();
 

src/bin/pg_dump/pg_dump.c

@@ -5407,6 +5407,17 @@ dumpBinaryUpgrade(Archive *fout, DumpableObject **dobjs, int numObjs)
 	if (!binary_upgrade || dataOnly)
 		return;
 
+	/*
+	 * We only support binary upgrades from GPDB versions based on
+	 * PostgreSQL 8.2 and higher. This is different from PostgreSQL
+	 * where the lower limit is at 8.3 since the on-disk format
+	 * changes introduced in 8.3 aren't supported in the upstream
+	 * version of pg_upgrade. The GPDB version of pg_upgrade does
+	 * however handle these changes.
+	 */
+	if (fout->remoteVersion < 80200)
+		return;
+
 	for (i = 0; i < numObjs; i++)
 	{
 		DumpableObject *dobj = dobjs[i];