tests/test-manifest-merging

parsers.c: fix integer overflows

thanks to zzuf for helping finding those

#!/bin/sh

echo % init foo-base
hg init foo-base

echo % create alpha in first repo
cd foo-base
echo 'alpha' > alpha
hg ci -A -m 'add alpha' -d '1 0'
cd ..

echo % clone foo-base to foo-work
hg clone foo-base foo-work

echo % create beta in second repo
cd foo-work
echo 'beta' > beta
hg ci -A -m 'add beta' -d '2 0'
cd ..

echo % create gamma in first repo
cd foo-base
echo 'gamma' > gamma
hg ci -A -m 'add gamma' -d '3 0'
cd ..

echo % pull into work and merge
cd foo-work
hg pull -q
hg merge

echo % revert to changeset 1 to simulate a failed merge
rm alpha beta gamma
hg up -C 1