即使在执行 git add -A 之后，当我运行 git status 时，我得到了这个：
# On branch master
# Changes not staged for commit:
# (use "git add <file>..." to update what will be committed)
# (use "git checkout -- <file>..." to discard changes in working directory)
# (commit or discard the untracked or modified content in submodules)
#
# modified: src/cartographer (modified content, untracked content)
# modified: src/cartographer_ros (untracked content)
#
no changes added to commit (use "git add" and/or "git commit -a")
知道如何解决这个问题吗？