For create/dropdb, only connect once to the server since we now have a

shared description table for pg_database comments.

Also update comments about database name selection.

src/bin/scripts/dropdb.c

@@ -113,6 +113,11 @@ main(int argc, char *argv[])
 	appendPQExpBuffer(&sql, "DROP DATABASE %s;\n",
 					  fmtId(dbname));
 
+    /*
+     * Connect to the 'postgres' database by default, except have
+     * the 'postgres' user use 'template1' so he can drop the
+     * 'postgres' database.
+     */
 	conn = connectDatabase(strcmp(dbname, "postgres") == 0 ? "template1" : "postgres",
 						   host, port, username, prompt_password, progname);