I've looked around in database.cc and found that out as well. The
problem here seems to be that a delta which comes as packet into a local
db has no size information attached for the new file version one is able
to create with it and of course, recreating a file locally just to find
out how big it is, is stupid. I wonder if it would be possible to
somehow smartly add up the sizes of the file deltas to get the complete
file size? If I look at the unified diff output I'd say yes, because one
could simply add up all bytes after a "-" prefixed line, and also those
after a "+" prefixed line, would calculate the difference of both and
add it up to the former file size.
Wouldn't it be easier to store in the database the size delta, for each
delta? Then you just sum them all across the file history to get the
final size.