Created attachment 348492 [details]
incorrect display of some parents

Run the script below to create a repository and check how it's displayed. Notice the following problems in the attached screenshot:
- the parent of b1 should be x, but it appears with no parent
- the 2nd parent of the two merge-master-in-b commits point to nowhere, where they should point to m1 (blue) and m2 (red)

#!/bin/bash
rm -rf /tmp/x1
mkdir /tmp/x1
cd /tmp/x1
git init
echo "1" > x; git add x; git commit -m "x"

git checkout -b b
echo "1" > b1; git add b1; git commit -m "b1"

git checkout master
echo "1" > m1; git add m1; git commit -m "m1"

git checkout b
git merge master -m merge-master-in-b
echo "1" > b2; git add b2; git commit -m "b2"

git checkout master
echo "1" > m2; git add m2; git commit -m "m2"

git checkout b
git merge master -m merge-master-in-b
echo "1" > b3; git add b3; git commit -m "b3"

git checkout master
echo "1" > m3; git add m3; git commit -m "m3"
git merge b -m merge-master-in-b