I've used this script to synchronize two gitolite installation after permissions has been set in the new repository. Needs password less ssh or ssh agent to work. Can be executed multiple times.

migrate-repositories.sh

#!/bin/sh

[ $DEBUG ] && set -x

WORKDIR=/tmp/repos
OLD_HOST=git.example.org
OLD_USER=gitolite
NEW_HOST=git.example.com
NEW_USER=gitolite
REPOS='comma,separated,list,of,repositories'
IFS=','

[ -d $WORKDIR ] || mkdir -p $WORKDIR
cd $WORKDIR

for repo in $REPOS; do
  echo "Migrating '$repo' to new host $NEW_HOST"
  # Clone a full copy of existing repository
  [ -d $repo.git ] || git clone --mirror $OLD_USER@$OLD_HOST:$repo
  cd $repo.git
  # This is used if script is invoked multiple times to fetch new updates
  git fetch -q --all
  # Add new origin if not present
  git remote | grep new_origin > /dev/null || git remote add new_origin $NEW_USER@$NEW_HOST:$repo
  # Push everything to new location, doesn't handle forced push in old repository (which is bad)
  git push --all new_origin
  git push --tags new_origin
  cd $WORKDIR
done