git merge problem

[Neal Becker]

Andreas Schwab wrote:

> Neal Becker <ndbecker2 at gmail.com> writes:
> 
>> fedpkg switch-branch f13
>> Branch f13 set up to track remote branch f13/master from origin.
>> [nbecker at nbecker1 unuran]$ git merge master
>> Auto-merging .gitignore
>> CONFLICT (add/add): Merge conflict in .gitignore
> 
> Apparently this is the first time you merge master into f13 since the
> git conversion.  You can use "git merge -X theirs master" to overwrite
> the files with the versions from master.  You only need to do this once
> for any branch that was never merged in git.
> 
> Andreas.
> 

But why did the same procedure work for f14 but not f13?