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#!/bin/bash
set -x
# Take some random github repo
repo=${1:-ingydotnet/boolean-pm}
# Delete test dir
rm -fr test-repo
# Clone repo into test dir
git clone "git@github.com:$repo" test-repo
(
# cd into test-repo
cd test-repo
# Tag original head
git tag o
# Pick a commit in the middle of the commit history
S=$(git rev-parse HEAD^^^^)
# Reset to the middle commit
git reset --hard $S
# Tag that history as 'a'
git tag a
# Reset to original
git reset --hard o
# Take the tail of the history.
git filter-branch -f --parent-filter "sed 's/-p $S//'" $S..HEAD
# Mark that sequence as 'b'
git tag b
# Reset to a
git reset --hard a
# Add a commit
echo foobar >> README
git commit README -m 'a change'
# Tag as a2
git tag a2
# Find commits for top of 'a' and root of 'b'
A=$(git rev-parse a)
RB=$(git rev-list --max-parents=0 b)
# Graft them together
echo "$RB $A" >> .git/info/grafts
git rebase --abort; git rebase -s recursive -X patience a2 b
# # Make the graft permanent. ie join head+tail
# # The commits should rewrite to match original history
# git filter-branch -f $RB^..b
# # Get commits for new 'b' and original
# B=$(git rev-parse b)
# O=$(git rev-parse o)
# # Check to see if it works
# if [ "$B" == "$O" ]; then
# echo "It worked: $B"
# else
# echo "If failed: $B, $O"
# fi
bash
)
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