fatal refusing to merge unrelated histories git code example

Example 1: fatal: refusing to merge unrelated histories

git pull origin master --allow-unrelated-histories

Example 2: git unrelated histories

git merge upstream/master --allow-unrelated-histories

Example 3: fatal: refusing to merge unrelated histories

git pull origin branchname --allow-unrelated-histories

Example 4: fatal: refusing to merge unrelated histories

git pull origin master --allow-unrelated-histories