tests/test-requires

test-merge-tools: windows fixes

- /bin/cat does not exist, expect 'cat'
- non-interactive mode is not correctly detected in pysh, force it

#!/bin/sh

mkdir t
cd t
hg init
echo a > a
hg add a
hg commit -m test -d "1000000 0"
rm .hg/requires
hg tip
echo indoor-pool > .hg/requires
hg tip

true