Update parsing of headers

Remove wrong `.replace()` statement which breaks any language file from a language ending with the character `n`. It is unclear to me why this replace is even there. As it is even invalid to replace without supplying a string with what it needs to be replaced.

**This problem:**
a PO file with `Language: en/n` is parsed as `eundefined` because the ending `n` is replaced with a missing variable.

**The Fix in this pull request:**
the replace is removed all together as it suits no real purpose.