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 a
% check custom patch options are honored
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adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
applying ../a.diff
Using custom patch
nothing changed