When working with branches, often you are focusing on a specific part of the codebase. Sometimes, a commit in a string of commits can cause failures elsewhere. Check out my script on bisecting the current branch and catch the commit that introduced the error.
The text you are looking for isn't in the current revision anymore, and so you'll have to dig through the Git history somehow, looking for when it was removed/introduced. Read about how I approached this from a CLI perspective, using a script to simplify these searches for me.