self_update of components, e.g. for vmnipkow9;

--- a/src/Pure/Admin/build_history.scala	Thu Nov 03 17:51:10 2016 +0100
+++ b/src/Pure/Admin/build_history.scala	Fri Nov 04 11:37:24 2016 +0100
@@ -403,6 +403,9 @@
             isabelle_hg.id()
           }
         isabelle_hg.update(rev = rev, clean = true)
+        ssh.execute(
+          ssh.bash_path(isabelle_repos_self + Path.explode("bin/isabelle"))
+            + " components -a").check
         ssh.execute(ssh.bash_path(isabelle_admin + Path.explode("build")) + " jars_fresh").check
         rev
       }