Allow the changegroup generator to completely load the buffer. This makes is possible to delete or truncate away revisions and still use the changegroup later.

#!/bin/sh

mkdir t
cd t
hg init
echo a > a
hg add a
hg commit -m "test" -d "0 0"
hg verify
hg parents
hg status
hg undo
hg verify
hg parents
hg status