underscore (_) conversion not working if not preceeded by a space

```
What steps will reproduce the problem?
1. having a sting like August,29th_to:_ August,30th
2. there is no space before the leading "_"
3.

What is the expected output? What do you see instead?
We expect to see the bolded "to:", we have _to:_ instead

What version of the product are you using? On what operating system?

Please provide any additional information below.

```

Original issue reported on code.google.com by `dmar...@allscenes.com` on 13 Sep 2012 at 11:25