xbstream sparse files support doesn't work on XFS

mysql> CREATE TABLE a( id int primary key auto_increment, a varchar(100), b varchar(100), c blob) COMPRESSION='zlib';
mysql> INSERT INTO a SET a = now(), b=now(), c=repeat(now(),3000);
mysql> INSERT INTO a (a,b,c) SELECT a,b,c FROM a;
…
mysql> INSERT INTO a (a,b,c) SELECT a,b,c FROM a; 

# xtrabackup --backup --stream=xbstream > a.xbs

xbstream -x <a.xbs 

root@debian:/tmp/xfs/test# du -sh a.ibd
520M    a.ibd
root@debian:/tmp/xfs/test# du -sh --apparent-size a.ibd
520M    a.ibd

root@debian:/tmp/a/test# du  -sh a.ibd
136M    a.ibd
root@debian:/tmp/a/test# du -sh --apparent-size a.ibd
520M    a.ibd