src/Pure/Tools/phabricator.scala

           Isabelle_System.download_file(mercurial_source, archive)
           archive
         }
         else Path.explode(mercurial_source)
 
-      Isabelle_System.gnutar("-xzf " + File.bash_path(archive), dir = tmp_dir).check
+      Isabelle_System.extract(archive, tmp_dir)
       val build_dir = File.get_dir(tmp_dir, title = mercurial_source)
 
       progress.bash("make all && make install", cwd = build_dir.file, echo = true).check
     }
   }