Don't attempt to parse empty response from server
Don't attempt to parse empty response from server

I couldn't trigger this until I hacked up stuff elsewhere to return
artificial failures, but still...

Signed-off-by: David Woodhouse <b460d66aaf00c296a3db1c1d9eeafc081d5f7d70@intel.com>

liiir1985/openconnect,nmav/openconnect-mine,neshema/openconnect,brandt/openconnect,mtmiller/openconnect,lins05/openconnect,neshema/openconnect,brandt/openconnect,lins05/openconnect,nmav/openconnect-mine,liiir1985/openconnect,chadcatlett/openconnect,atyndall/openconnect,atyndall/openconnect,chadcatlett/openconnect,nmav/openconnect-mine,don-johnny/openconnect,mtmiller/openconnect,atyndall/openconnect,mtmiller/openconnect,cernekee/openconnect,cernekee/openconnect,don-johnny/openconnect,mveplus/openconnect-client,cernekee/openconnect,lins05/openconnect,neshema/openconnect,chadcatlett/openconnect,brandt/openconnect,mveplus/openconnect-client,don-johnny/openconnect,matlockx/openconnect,atyndall/openconnect,matlockx/openconnect,brandt/openconnect,cernekee/openconnect,chadcatlett/openconnect,mveplus/openconnect-client,matlockx/openconnect,liiir1985/openconnect,mveplus/openconnect-client,liiir1985/openconnect,nmav/openconnect-mine,mtmiller/openconnect,don-johnny/openconnect,neshema/openconnect,matlockx/openconnect,lins05/openconnect