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

echo "[extensions]" >> $HGRCPATH
echo "mq=" >> $HGRCPATH

hg init a
cd a
echo a > a
hg ci -Ama

hg qnew a.patch
echo a >> a
hg qrefresh

hg qnew b.patch
echo b > b
hg add b
hg qrefresh

hg qnew c.patch
echo c > c
hg add c
hg qrefresh

hg qgoto a.patch
hg qgoto c.patch
hg qgoto b.patch