The source control system can’t merge the two file versions until Barb resolves the conflict between black bear and brown bear (the additions of wolf and fox still cause no problem).
When conflicts of this nature arise, someone must examine the comparison and determine which version of bear should win out. In this case, Barb decides to go with black bear.
It’s worth considering the risk associated with this merge process. Barb’s commit fails, so she can’t save her changes to the repository until she can successfully perform a merge. If something goes wrong with the merge operation, she risks losing her changes entirely. This might be a minor problem for small textual changes like these, but a big problem if she’s trying to merge in substantial and complex changes to application logic. This is why the source control mantra is: commit small changes often.
The article is more of an intro to source control, but if you aren’t familiar with how source control works, it’s a great read. Regardless, the best thing you can do for yourself is to get your database code in source control. That opens up the possibility for safer refactoring of code.