icholy/ttygif — pull request #5 by tsl0922 (2013-08-20 02:52:28+00:00)
Title: fix libpng warning on OSX Mountain Lion

On OSX Mountain Lion, the `screencapture` command always outputs:

```
libpng warning: zero length keyword
libpng warning: Empty language field in iTXt chunk
```

This message will be inside the final gif image, redirect it to `/dev/null` can solve this problem.