test case of a git find-similar-branch function

#!/bin/bash

set -e

root=/tmp/gittest
mkdir -p $root

a=$root/a
b=$root/b

rm -RfI $a $b || true

genTestRepo() {
  local isB="$1"
  local r="$2"

  mkdir $r
  cd $r
  git init

  echo "abc def" > a.txt
  echo "xyz" > b.txt
  git add a.txt b.txt
  GIT_AUTHOR_DATE='Fri Feb 22 10:00:00 2013 +0100' git commit -m "commit 1 - $r"
  sleep 1

  if [ -z "$isB" ]; then # make some garbage
    echo "1 2 3" >>z.txt
    git add z.txt
    GIT_AUTHOR_DATE='Fri Feb 22 11:00:00 2013 +0100' git commit -m "commit 1b * $r"
    sleep 1
  fi

  echo "123" > c.txt
  git add c.txt
  GIT_AUTHOR_DATE='Fri Feb 22 12:00:00 2013 +0100' git commit -m "commit 2 - $r"
  sleep 1

  if [ -n "$isB" ]; then # make some garbage
    echo "A B C" >>x.txt
    git add x.txt
    GIT_AUTHOR_DATE='Fri Feb 22 13:00:00 2013 +0100' git commit -m "commit 2b * $r"
    sleep 1
  fi

  rm b.txt
  git rm b.txt
  GIT_AUTHOR_DATE='Fri Feb 22 14:00:00 2013 +0100' git commit -m "commit 3 - $r"
  sleep 1

  rm a.txt
  echo "another line" >a.txt
  git add a.txt
  GIT_AUTHOR_DATE='Fri Feb 22 15:00:00 2013 +0100' git commit -m "last common commit"
  sleep 1

  if [ -n "$isB" ]; then # make this branch newer
    echo "2nd line" >>a.txt
    git add a.txt
    GIT_AUTHOR_DATE='Fri Feb 22 16:00:00 2013 +0100' git commit -m "commit 4 * $b"
    sleep 1

    echo "xxx" >d.txt
    git add d.txt
    GIT_AUTHOR_DATE='Fri Feb 22 17:00:00 2013 +0100' git commit -m "commit 5 * $b"
    sleep 1
  fi

  git log | cat
}

genTestRepo ""  "$a"
genTestRepo "1" "$b"

echo "== rebase new master =="
cd $b
git branch -m master master_tmpnew
git remote add origin file://$a
git fetch origin master:refs/remotes/origin/master
git checkout master

#echo "== rebase new master (easy way) =="
#git checkout master_tmpnew
#git rebase master

echo "== rebase new master (safe way) =="
echo "  find:"
lastbr=
lastrest=
revU=  # Update
revB=  # Base
rm -f rev.*.tmp
(
  git log --format='format:b %H %at %an %ae %f' master
  echo
  git log --format='format:u %H %at %an %ae %f' master_tmpnew
) | sort -r -t' ' -k3 | while read br rev rest; do
  echo "? $br $rev $rest"
  [ "$br" != "u" ] || revU="$rev"
  [ "$br" != "b" ] || revB="$rev"
  if [ "$lastrest" = "$rest" -a "$lastbr" != "$br" ]; then
    echo "found match: base $revB  updae $revU"
    echo "$revB" >rev.base.tmp
    echo "$revU" >rev.update.tmp
    break
  fi
  lastrest="$rest"
  lastbr="$br"
done
echo "  do:"
if [ ! -f rev.base.tmp ]; then
  echo "No matching revision found"
  exit 1
fi
revB="`cat rev.base.tmp`"
revU="`cat rev.update.tmp`"
git rebase --onto $revB $revU master_tmpnew

echo "== merge =="
git checkout master
git merge --ff-only master_tmpnew

echo "== log =="
#echo "== push =="
#git push origin master
git log | cat

echo "done."