mruby/mruby — pull request #693 by masamitsu-murase (2013-01-05 20:24:57+00:00)
Title: Modify NODE_IF handling.

`unless` without `else` sometimes causes strange result.

When `unless` is used without `else`, `tree->cdr->car` of `NODE_IF` is `NULL`.
In this case, `pop()` should not be called because `codegen` generates no code.

This is a sample to reproduce this issue.

```ruby
def test(&block)
buf = nil
block.call(buf) unless (false)
end

test do |i|
p i # nil is expected.
end
```

Without this patch, the above code outputs as follows:

```
#
```