git pull로 가져온 코드가 업데이트되지 않으면 어떻게 해야 하나요?

$ git pull
There is no tracking information for the current branch.
Please specify which branch you want to merge with.
See git-pull(1) for details.
git pull
If you wish to set tracking information for this branch you can do so 
with:
git branch --set-upstream-to=/ master

$ git pull
From REPOSITORY_URL
* branch master -> FETCH_HEAD
a152b19..171e4a2 master -> origin/master
Updating a152b19..171e4a2
error: Your local changes to the following files would be overwritten by 
merge:
file1.txt
file2.txt
Please commit your changes or stash them before you merge.
Aborting

$ git stash
Saved working directory and index state WIP on master: d91368b Previous 
commit message
$ git pull
From REPOSITORY_URL
* branch master -> FETCH_HEAD
a152b19..171e4a2 master -> origin/master
Updating a152b19..171e4a2
Fast-forward
file1.txt | 1 +
file2.txt | 1 +
2 files changed, 2 insertions(++)
$ git stash apply

$ git commit -am 'Committing two files before git-pull'
[master d91368b] Committing two files before git-pull
2 files changed, 2 insertions(++)
$ git pull
From REPOSITORY_URL
* branch master -> FETCH_HEAD
a152b19..171e4a2 master -> origin/master
Updating a152b19..171e4a2
Fast-forward
file1.txt | 1 +
file2.txt | 1 +