Needs an environment variable named GIT_SVN_URL that points to the branches folder of the SVN repo you're tracking, ie. export GIT_SVN_URL=https://your.repo.com/project/branches and then you can git-svn-pull-branch <svn branch> <local name> <rev spec>

git-svn-pull-branch

#!/bin/sh

CMD=$(basename $0)

if [ $# != 3 ]; then
  echo "usage $CMD <svn branch> <local name> <rev spec>"
  exit 1
fi

if [ ! -d .git ]; then
  echo "Not a git workspace"
  exit 1
fi

BRANCH=$1
LOCAL_NAME=$2
REV=$3
SVN_URL="$GIT_SVN_URL/$BRANCH"

svn_find_rev()
{
  cut -f 1 '-d ' | sed -e 's/^r//'
}

svn_find_first_rev()
{
  tail -n +2 | head -1 | svn_find_rev
}

svn_find_last_rev()
{
  SAWSEP=0
  LASTREV=
  while read line; do
    if [ $SAWSEP == 1 ]; then
      NEXTREV=$(echo $line | svn_find_rev)
      if [ "x$NEXTREV" != "x" ]; then
        LASTREV=$NEXTREV
      fi
      SAWSEP=0
    elif [ "$line" == "$SEP" ]; then
      SAWSEP=1
    fi
  done

  echo $LASTREV
}

if [ "$REV" = "HEAD" ]; then
  REV=$(svn log -l 1 $SVN_URL | svn_find_first_rev)
elif [ "$REV" = "PARENT" ]; then
  REV=$(svn log --stop-on-copy $SVN_URL | svn_find_last_rev)
elif [ "$REV" = "ALL" ]; then
  false
fi

NREV=$(expr $REV + 0 2> /dev/null)
if [ "x$NREV" != "x" ]; then
  BRANCHPREFIX=$(basename $BRANCH | sed -e 's/_branch$//')
  if [ "$(fgrep "[svn-remote \"$BRANCH\"]" .git/config)" != "" ]; then
    echo "$BRANCH already in this git"
    exit 1
  fi

  echo "Registering $BRANCH with git"
  cat <<EOF >> .git/config

[svn-remote "$BRANCH"]
  url = $SVN_URL
  fetch = :refs/remotes/$BRANCH
EOF

  echo "Fetching base revision $NREV"
  git svn fetch -R $BRANCH -r $NREV || exit 1
  git branch --track $LOCAL_NAME $BRANCH || exit 1
  echo "Checking out $BRANCH"
  git checkout $LOCAL_NAME || exit 1
  echo "Updating $LOCAL_NAME"
  git svn rebase || exit 1
else
  echo "Cannot resolve rev spec '$REV'"
  exit 1
fi