When indexing a file with ref deltas, a temporary cache for the
offsets has to be built, as we don't have an index file yet. If the
user takes the responsiblity for filling the cache, the packing code
will look there first when it finds a ref delta.
Signed-off-by: Carlos Martín Nieto <carlos@cmartin.tk>
The callers immediately throw away the offset, so we don't need any
logical changes in any of them. This will be useful for the indexer,
as it does need to know where the compressed data ends.
Signed-off-by: Carlos Martín Nieto <carlos@cmartin.tk>
