storage: crappy fix of possible issue with find_space not handling pool overhead of volumes

ccnode/libvirtwrapper.py

@@ -415,7 +415,8 @@ class LibvirtHVStorage(HVStorage):
         '''
         for pool in self._pools.iteritems():
             try:
-                if new_space * GIGABYTE_DIV < pool[1].info()[3]:
+                # FIXME, crappy overhead delta
+                if new_space * GIGABYTE_DIV <= pool[1].info()[3] - MEGABYTE_DIV:
                     return (pool)
             except libvirt.libvirtError as e:
                 raise StorageError("Can't get pool informations (%s)" % e)