Re: surprising behavior from merge

From: Sebastian Kuzminsky <seb@highlab.com>
Date: May 14, 2012, 18:14 UTC
Message-ID: <8F6454B6-5C93-45AA-8AB0-881FEEE22848@highlab.com>
In-Reply-To: <4FADCA05.60109@blizzard.com>

Here's a little script that reproduces the problem:

----- #!/bin/bash set -e

if [ -e git-merge-problem ]; then
    echo "'git-merge-problem' exists, not running test!"
    exit 1
fi

mkdir git-merge-problem cd git-merge-problem git init

echo "first line" > myfile echo "second line" >> myfile echo "" >> myfile echo "next to last line" >> myfile echo "final line" >> myfile git add myfile git commit -m 'initial commit of myfile'

git branch other

sed -i -e 's/second line/this line is in the context of the crucial patch/' myfile git add myfile git commit -m 'change context for crucial patch'

sed -i -e 's/^$/\nthis line is added only once, but in two branches\n/' myfile git add myfile git commit -m 'add a line'

git tag add-a-line

git checkout other git cherry-pick -x add-a-line

git checkout master

git merge other

NUM_LINES=$(grep 'added only once' myfile | wc -l)
if [ $NUM_LINES -eq 2 ]; then
    echo "FAIL!  the merge added the line twice"
    cat myfile
    exit 1
elif [ $NUM_LINES -ne 1 ]; then
    echo "FAIL!  the merge added the line a strange number of times ($NUM_LINES)"
    exit 1
fi

echo "PASS! the merge added the line just once!" exit 0 -----

On May 11, 2012, at 20:25 , Illia Bobyr wrote:

Show 31 quoted lines

> On 5/11/2012 5:05 PM, Sebastian Kuzminsky wrote:
>> On 05/11/2012 05:57 PM, Michael Witten wrote:
>>> On Fri, 11 May 2012 16:25:29 -0600, Sebastian Kuzminsky wrote:
>>> 
>>>> The simplified repo is here if anyone wants to inspect it:
>>>> https://github.com/SebKuzminsky/merge-problem
>> ...
>> 
>>> In other words, rather than burdening people with the task of
>>> constructing a mental picture of what you have done, you should
>>> show them as directly and precisely as possible; in this way,
>>> people can go about the business of discussing your issue much
>>> more quickly and, most importantly, PRECISELY.
>>> 
>> 
>> Ah, I had intended the extremely tiny git repo I linked to to provide 
>> the info in the most concise way possible.  The surprising behaviour 
>> happened at the final commit in the repo, which was made by 'git merge 
>> other'.
>> 
>> I can email a list of commands to reproduce the issue later tonight if 
>> that would make anything clearer.
> 
> The repository you provided is actually quite simple and clear, though I 
> have no idea why this might be happening.  Or if it is an expected behavior.
> 
> At the same time if you provide a list of command if someone will be 
> fixing this they may server as an automated test.  Git has a lot of them.
> 
> --
> Illia Bobyr

-- 
Sebastian Kuzminsky