The wiki markup is not correctly processed if formatting begins or ends in the middle of words

The wiki markup is not correctly processed if formatting begins or ends in the middle of words.

How to reproduce:

1. Add to a description of the Text below:
   
2. Exporting the description with the wiki returns this:
   

So, if the entire formating element is applied to the entire word, it works.
It fails if only a part of the word is selected.