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

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>