Bug in log for path in case of identical commit

>
> To be more clear, there is a script in attachment to reproduce, but
> here is the result :
> $ git log --graph --oneline --all --decorate --name-status
> *   63c807f (HEAD, master) Merge branch 'branch' into 'master'
> |\
> | * 5dc8785 (branch) Change line 15 on branch
> | | M   file
> | * d9cd3ce Change line 25 on branch
> | | M   file
> * | 7220d52 Change line 15 on master
> |/
> |   M   file
> * 7566672 Initial commit
>   A     file
>
> $ git log --graph --oneline --all --decorate --name-status -- file
> * 5dc8785 (branch) Change line 15 on branch
> | M     file
> * d9cd3ce Change line 25 on branch
> | M     file
> * 7566672 Initial commit
>   A     file
>
> => The commit 7220d52 modified the file but is not shown in file
> history anymore.
> The expected result would be:
> * 5dc8785 (branch) Change line 15 on branch
> | M     file
> * d9cd3ce Change line 25 on branch
> | M     file
> | * 7220d52 Change line 15 on master
> |/
> |   M   file
> * 7566672 Initial commit
>   A     file
>
> The order between the 2 commits on the branch is not important.
> If you do a 'cherry-pick 7220d52' or a 'merge --squash master' instead
> of applying the same modification for commit 5dc8785, you get the same
> result (cherry-picking was my initial use-case).
> If you do not create the commit d9cd3ce, then the file history show all commits.
> If you merge 'master' into 'branch', then the file history show all commits.
>
> Am I missing something or is it really a bug?
> Thanks.

> When merging 2 branches with the same modifications on the both sides,
> depending the merge side, one branch disappear from the file history.
>
> To be more clear, there is a script in attachment to reproduce, but
> here is the result :
> $ git log --graph --oneline --all --decorate --name-status
> *   63c807f (HEAD, master) Merge branch 'branch' into 'master'
> |\
> | * 5dc8785 (branch) Change line 15 on branch
> | | M   file
> | * d9cd3ce Change line 25 on branch
> | | M   file
> * | 7220d52 Change line 15 on master
> |/
> |   M   file
> * 7566672 Initial commit
>   A     file
>
> $ git log --graph --oneline --all --decorate --name-status -- file
> * 5dc8785 (branch) Change line 15 on branch
> | M     file
> * d9cd3ce Change line 25 on branch
> | M     file
> * 7566672 Initial commit
>   A     file
>
> => The commit 7220d52 modified the file but is not shown in file
> history anymore.
> The expected result would be:
> * 5dc8785 (branch) Change line 15 on branch
> | M     file
> * d9cd3ce Change line 25 on branch
> | M     file
> | * 7220d52 Change line 15 on master
> |/
> |   M   file
> * 7566672 Initial commit
>   A     file
>
> The order between the 2 commits on the branch is not important.
> If you do a 'cherry-pick 7220d52' or a 'merge --squash master' instead
> of applying the same modification for commit 5dc8785, you get the same
> result (cherry-picking was my initial use-case).
> If you do not create the commit d9cd3ce, then the file history show all commits.
> If you merge 'master' into 'branch', then the file history show all commits.

> On Fri, Oct 31, 2014 at 4:40 AM, Alexandre Garnier <zigarn+git@gmail.com> wrote:
>> When merging 2 branches with the same modifications on the both sides,
>> depending the merge side, one branch disappear from the file history.
>>
>> To be more clear, there is a script in attachment to reproduce, but
>> here is the result :
>> $ git log --graph --oneline --all --decorate --name-status
>> *   63c807f (HEAD, master) Merge branch 'branch' into 'master'
>> |\
>> | * 5dc8785 (branch) Change line 15 on branch
>> | | M   file
>> | * d9cd3ce Change line 25 on branch
>> | | M   file
>> * | 7220d52 Change line 15 on master
>> |/
>> |   M   file
>> * 7566672 Initial commit
>>   A     file
>>
>> $ git log --graph --oneline --all --decorate --name-status -- file
>> * 5dc8785 (branch) Change line 15 on branch
>> | M     file
>> * d9cd3ce Change line 25 on branch
>> | M     file
>> * 7566672 Initial commit
>>   A     file
>>
>> => The commit 7220d52 modified the file but is not shown in file
>> history anymore.
>> The expected result would be:
>> * 5dc8785 (branch) Change line 15 on branch
>> | M     file
>> * d9cd3ce Change line 25 on branch
>> | M     file
>> | * 7220d52 Change line 15 on master
>> |/
>> |   M   file
>> * 7566672 Initial commit
>>   A     file
>>
>> The order between the 2 commits on the branch is not important.
>> If you do a 'cherry-pick 7220d52' or a 'merge --squash master' instead
>> of applying the same modification for commit 5dc8785, you get the same
>> result (cherry-picking was my initial use-case).
>> If you do not create the commit d9cd3ce, then the file history show all commits.
>> If you merge 'master' into 'branch', then the file history show all commits.
>
> This last line was confusing to me.  But I think you've misinterpreted
> the results a bit.  There is no difference between "merge master into
> branch" and "merge branch into master" in this case.  The real reason
> the "extra" commit is shown in the former case is that you used
> '--all' (include all refs as commandline arguments) and the commit
> which was being omitted was directly referenced by a ref, 'master'.
>
> When I remove the "--all" from your test script, I get consistent logs
> for the two merges.
>
> Maybe this has misled your other tests as well.  Read the "History
> Simplification" section of "git help log".