删除名字含有特定前缀的git仓库分支

我想保留一个仓库中以特定字符串为前缀的分支，还想按照commit时间保留同一前缀的指定数量的分支，删除分支的脚本如下：

#!/usr/bin/env python
#-*- coding:utf8 -*-
#coding:utf-8

import os

user_prefix = ["swh", "hzz", "sxwang", "junfeng", "fsh", "sxl", "chenwei", "weiyang", "chiyang", "smj", "hyc", "zmh", "hsy", "xsk", "zzh","dasituer", "kjq", "shuolin", "zc", "lll", "lhy"]
reserve_prefix = ["oushudb", "hawq"]
branch_save_num = 2
output_file = '/tmp/delete_cmd'
        

if __name__ == '__main__':
    fp = open(output_file, "w")
    if os.system("git fetch --prune"):
        print("Should in git repository.")

    lines = []
    # get all branch to be deleted belonging to users
    for user in user_prefix:
        cmd = "git for-each-ref refs/remotes/origin/{}* --format=\'%(committerdate:short) %09 %(refname:short)\' | sort -k1,1r".format(user)
        branchs = os.popen(cmd)

        delete_stat = "git push origin :"
        num = 0
        for branch in branchs:
            if len(branch.strip("\n")) == 0:
                continue
            if num >= branch_save_num:
                lines.append(delete_stat + branch.split("\t")[1].split("/")[1])
            num += 1

    # get all branch not in user list and reserve list
    filter = "HEAD\|"
    for user in user_prefix:
        filter += user + "\|"
    for reserve in reserve_prefix:
        filter += reserve + "\|"
    filter = filter[:len(filter)-2]
    cmd = "git for-each-ref refs/remotes/origin/ --format=\'%(committerdate:short) %09 %(refname:short)\' | grep -v \'{}\' | sort -k1,1".format(filter)
    branchs = os.popen(cmd)
    for branch in branchs:
        lines.append(delete_stat + branch.split("\t")[1][8:])
    
    fp.writelines(lines)
    fp.close()