Reduce ram used for very large inlined index files During a clone, an inline index is not converted to a split index file until the very end. When the conversion happens, the index can be very large, and the inline index loading functions always load the entire index file into ram. This changes the revlog code to read the index in smaller chunks.

#!/bin/sh
#
mkdir t
cd t
hg init
echo 0 > a
echo 0 > b
hg ci -A -m m -d "1000000 0"
hg rm a
hg cat a
sleep 1 # make sure mtime is changed
echo 1 > b
hg ci -m m -d "1000000 0"
echo 2 > b
hg cat -r 0 a
hg cat -r 0 b
hg cat -r 1 a
hg cat -r 1 b