remus: write circumlocution for try..except..finally

Parsing /otc/source/vtd/xen-unstable/tools/python/../../tools/libxl/libxl.idl
  File "/usr/lib64/python2.4/site-packages/xen/remus/save.py", line 169
    finally:
          ^
SyntaxError: invalid syntax

This was introduced in 23195:13ec53a59a42
It is a problem for Python 2.4 and earlier, only.

So use try...(try...except)...finally as suggested by Ian Campbell.

Signed-off-by: Liu, Jinsong <jinsong.liu@intel.com>
Acked-by: Shriram Rajagopalan <rshriram@cs.ubc.ca>
Acked-by: Ian Campbell <Ian.Campbell@eu.citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>

tools/python/xen/remus/save.py

@@ -161,11 +161,12 @@ class Saver(object):
 
         self.checkpointer = xen.lowlevel.checkpoint.checkpointer()
         try:
-            self.checkpointer.open(self.vm.domid)
-            self.checkpointer.start(self.fd, self.suspendcb, self.resumecb,
-                                    self.checkpointcb, self.interval)
-        except xen.lowlevel.checkpoint.error, e:
-            raise CheckpointError(e)
+            try:
+                self.checkpointer.open(self.vm.domid)
+                self.checkpointer.start(self.fd, self.suspendcb, self.resumecb,
+                                        self.checkpointcb, self.interval)
+            except xen.lowlevel.checkpoint.error, e:
+                raise CheckpointError(e)
         finally:
             try: #errors in checkpoint close are not critical atm.
                 self.checkpointer.close()