grep: display correct user/revision for --all in reverse. Also handle multiple occurrences of the same line by storing linestates in an array instead of a dict, and using difflib to compute the difference between linestates.

#!/bin/sh

mkdir t
cd t
hg init
echo a > a
hg add a
hg commit -m test -d "1000000 0"
hg history
hg manifest
hg cat a
hg verify