On a 32-bit system, the maximum possible size for an object is less than
4GB, while 64-bit systems may cope with larger objects. Due to this
limitation, variables holding object sizes are using an unsigned long
type (32 bits on 32-bit systems, or 64 bits on 64-bit systems).
When large objects are encountered, and/or people play with large delta
depth values, it is possible for the maximum allowed delta size
computation to overflow, especially on a 32-bit system. When this
occurs, surviving result bits may represent a value much smaller than
what it is supposed to be, or even zero. This prevents some objects
from being deltified although they do get deltified when a smaller depth
limit is used. Fix this by always performing a 64-bit multiplication.
Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>