按照本手册将fedora从32升级到33。重启后，运行时dnf check-update出现如下错误：
Traceback (most recent call last):
File "/usr/bin/dnf", line 57, in <module>
from dnf.cli import main
ModuleNotFoundError: No module named 'dnf'
附加信息：
命令的输出rpm -qa python3是：
python3-3.9.1-2.fc33.x86_64
python3-3.8.7-2.fc32.x86_64
似乎即使升级到 fedora 33，旧的 fedora 32 软件包仍然存在。润rpm -qa | sort证明了这一点。
命令的输出rpm -ql python3-3.8.7-2.fc32.x86_64是：
/usr/bin/pydoc
/usr/bin/pydoc3
/usr/bin/pydoc3.8
/usr/bin/python3
/usr/bin/python3.8
/usr/lib/.build-id
/usr/lib/.build-id/da
/usr/lib/.build-id/da/2e3a5d2a850e1b6e560df11fa5d61a7192f954
/usr/share/doc/python3
/usr/share/doc/python3/README.rst
/usr/share/man/man1/python3.1.gz
/usr/share/man/man1/python3.8.1.gz
但输出python3-3.8.7-2.fc33.x86_6是：
error: open of python3-3.8.7-2.fc33.x86_64 failed: No such file or directory