python zip报出警告

简明python教程中有这么一个例子：

1. #!/usr/bin/python
   
2. # Filename: backup_ver1.py
   
3. 
   
4. import os
   
5. import time
   
6. 
   
7. source = ['/home/swaroop/byte', '/home/swaroop/bin']
   
8. 
   
9. target_dir = '/mnt/e/backup/' # Remember to change this to what you will be using
   
10. 
    
11. target = target_dir + time.strftime('%Y%m%d%H%M%S') + '.zip'
    
12. 
    
13. zip_command = "zip -qr '%s' %s" % (target, ' '.join(source))
    
14. 
    
15. # Run the backup
    
16. if os.system(zip_command) == 0:
    
17.     print 'Successful backup to', target
    
18. else:
    
19.     print 'Backup FAILED'

复制代码

source = ['/home/swaroop/byte', '/home/swaroop/bin'] 写成这种有同级别目录的路径，执行这个python脚本，没有异常，
而我写成 source = ['/data/test', '/home/swaroop/bin']  时却报很多行的这个警告，(test和bin都是目录)
zip warning: No such device or address
zip warning: No such device or address
zip warning: No such device or address
zip warning: No such device or address
zip warning: No such device or address
zip warning: No such device or address
zip warning: No such device or address
zip warning: No such device or address
zip warning: No such device or address
zip warning: No such device or address
zip warning: No such device or address
zip warning: No such device or address

这是啥情况？
如果 source = ['/home/swaroop/byte', '/home/swaroop/bin']
' '.join(source) 之后把source列表变成了 /home/swaroop/byte /home/swaroop/bin
zip_command = "zip -qr '%s' %s" % (target, ' '.join(source)) 相当于 zip_command = "zip -qr /mnt/e/backup/日期时间.zip /home/swaroop/byte /home/swaroop/bin 把/home/swaroop/目录下的 byte和bin目录添加到压缩文件中，

如果 source = ['/data/test', '/home/swaroop/bin'],  ' '.join(source) 之后把source列表变成了/data/test /home/swaroop/bin
zip_command = "zip -qr '%s' %s" % (target, ' '.join(source)) 相当于 zip_command = "zip -qr /mnt/e/backup/日期时间.zip /data/test /home/swaroop/bin 把/data/test目录下的文件或目录，和home/swaroop/bin目录下的文件或目录 添加到压缩文件中

这有什么不同吗？同样是两个目录，为什么source = ['/data/test', '/home/swaroop/bin']这样写的时候会报出警告？
而且测试时发现确实是把/data/test/ 和 /home/swaroop/bin两个目录压缩在了一个压缩文件中，只是执行脚本时却报出警告。
难道zip压缩时，不能将多个完全不同级别的目录放在一起压缩？