hgmerge: fix diff+patch detection; cleanups Details: - actually show help message when no tools are found - whitespace cleanup (stupid emacs) - quote more variables - simplify merge/diff3 error handling

#!/bin/sh

hg init
echo 123 > a
hg add a
hg commit -m "first" -d "0 0" a
mkdir sub
echo 321 > sub/b
hg add sub/b
hg commit -m "second" -d "0 0" sub/b
cat sub/b
hg co 0
cat sub/b
ls sub

true