我正在FFmpeg工作。我git克隆它的源代码。当我git status时，一切运作良好。
FFmpeg git:(master) git status
On branch master
Your branch is behind 'origin/master' by 2 commits, and can be fast-forwarded.
(use "git pull" to update your local branch)
nothing to commit, working tree clean
但现在我想将分支更改为release/3.4，某些文件已被更改。
FFmpeg git:(master) git checkout release/3.4
Switched to branch 'release/3.4'
Your branch is up-to-date with 'origin/release/3.4'.
FFmpeg git:(release/3.4) ✗ git status
On branch release/3.4
Your branch is up-to-date with 'origin/release/3.4'.
Untracked files:
(use "git add <file>..." to include in what will be committed)
libavcodec/codec_list.c
libavcodec/parser_list.c
libavdevice/indev_list.c
libavdevice/outdev_list.c
libavfilter/filter_list.c
libavformat/demuxer_list.c
libavformat/muxer_list.c
nothing added to commit but untracked files present (use "git add" to track)
我很困惑。我从未更改过这些文件。