按照文档升级，出现如下错误：
root@disk:/opt/seafile/seafile-server-7.1.1/upgrade# ./upgrade_7.0_7.1.sh
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This script would upgrade your seafile server from 7.0 to 7.1
Press [ENTER] to contiune
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renaming the gunicorn.conf to gunicorn.conf.py ...
Done
Updating seafile/seahub database ...
[INFO] You are using MySQL
[INFO] updating seahub database...
/opt/seafile/seafile-server-7.1.1/seahub/thirdpart/pymysql/cursors.py:170: Warning: (1050, "Table 'base_reposecretkey' already exists")
result = self._query(query)
[WARNING] Failed to execute sql: (1091, "Can't DROP 'drafts_draft_origin_file_uuid_7c003c98_uniq'; check that column/key exists")
Done
migrating avatars ...
Done
updating /opt/seafile/seafile-server-latest symbolic link to /opt/seafile/seafile-server-7.1.1 ...
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Upgraded your seafile server successfully.
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root@disk:/opt/seafile/seafile-server-7.1.1/upgrade#