[XM] Fix missing security check in block-attach

This patch fixes an indentation error in main.py. The effect of this
bug is that block-attach does not check labels if the ACM is
active. This bug slipped in with change set 11572_:_ ad22c711ccb7
<http://xenbits.xensource.com/xen-unstable.hg?cs=ad22c711ccb7>.

Signed-off by: Reiner Sailer <sailer@us.ibm.com>

tools/python/xen/xm/main.py

@@ -1261,7 +1261,7 @@ def parse_block_configuration(args):
         label = security.get_security_printlabel(dominfo)
     else:
         label = None
-        security.res_security_check(args[1], label)
+    security.res_security_check(args[1], label)
 
     return (dom, vbd)