revset: map postfix '%' to only() to optimize operand recursively (issue4670)
Instead of keeping 'onlypost' as a method, this patch rewrites it to 'only'
function. This way, 'x%' always has the same weight as 'only(x)'.
Testing that hghave does not crash when checking features $ "$TESTDIR/hghave" --test-features 2>/dev/null