Testcase for a possible git bug, which wasn't a bug you shouldn't use a "different' push url, instead use a pushdefault to a different remote.

gitbug.sh

rm -rf left/ right/ right.git/
git init left
cd left/
echo "hello world" > test.txt
git add test.txt 
git commit -m .
cd ..
git clone --bare left right.git
git clone right.git/ right
cd right
git remote set-url origin ../left
git remote set-url origin --push ../right.git
echo "bye world" >> test.txt 
git commit -a -m .
git push
git log
echo "start: two commits, ok"
git fetch
git rebase origin/master
git log
echo "manual fetch/rebase: two commits, still ok"
git pull --rebase
git log
echo "pull: one commits, oops?"