revlog: generate trivial deltas against null revision To avoid extra memory usage and performance issues with large files, generate a trivial delta header for deltas against the null revision rather than calling the usual delta generator. We append the delta header to meta rather than prepending it to data to avoid a large allocate and copy.

adding foo
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
adding foo
   rev    offset  length   base linkrev nodeid       p1           p2
     0         0       0      0       0 b80de5d13875 000000000000 000000000000
     1         0      24      0       1 0376abec49b8 000000000000 000000000000