while read oldrev newrev refname 
do
     if [[ "$newrev" != "0000000000000000000000000000000000000000" ]] ; then
          branch=${refname#refs/heads/} 
     fi
done

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这里有一个可能的循环，尽管我不清楚你想对远程分支或标记名和/或本地引用做什么：

#! /bin/sh
NULLSHA=0000000000000000000000000000000000000000 # 40 0's
say() {
    echo "$@" 1>&2
}
while read localref localhash foreignref foreignhash; do
    case $foreignref in
    refs/heads/*)
        reftype=branch
        shortref=${foreignref#refs/heads/};;
    refs/tags/*)
        reftype=tag
        shortref=${foreignref#refs/tags/};;
    *)  reftype=unknown-ref-type
        shortref=$foreignref;;
    esac
    say "pushing to $reftype $shortref"
    case $localhash,$foreignhash in
    $NULLSHA,*) say "(push with intent to delete)";;
    *,$NULLSHA) say "(push with intent to create)";;
    *) say "(push with intent to update from $foreignhash to $localhash)"
       # for branch updates only, let's see if it's a fast-forward
       if [ $reftype = branch ]; then
           if git merge-base --is-ancestor $foreignhash $localhash; then
               say "(this is a fast-forward)"
           else
               say "(this can only work if forced)"
           fi
       fi;;
    esac
done

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(note：这一点没有得到很好的测试）。