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.

#!/bin/sh

hg init
echo a > a
hg ci -Ama -d'0 0'
mkdir b
echo a > b/a
hg ci -Amb -d'1 0'
hg manifest
hg manifest -v
hg manifest --debug
hg manifest -r 0
hg manifest -r 1
hg manifest -r tip

echo % should fail
hg manifest -r 2
hg manifest -r tip tip

hg manifest tip