Git,refname不明确

Question

昨天，我从一个分支创建了一个分支，将它推到Origine，并将它合并回Master。您可以在这里看到：

$ history |less
 8358  git co master
 8359   commit # shortcut that adds all and commits
 8360  push # shortcut that `git push`'s
 8361  git lg # shortcut that logs my output
 8362  git co 1600
 8363  git co -b 1601
 8364  npm run test
 8365  npm run test
 8366  npm run test
 8367  npm run test
 8368  npm run test
 8369  npm run test
 8370  npm run test
 8371  npm run test
 8372  npm run test
 8373  npm run test
 8374  npm run test
 8375  npm run test
 8376  npm run test
 8377  ./release.sh
 8378  ./release.sh
 8379  commit
 8380  push
 8381      git push --set-upstream origin 1601
 8382  git lg
 8383  git co master
 8384  git merge --no-ff -
 8385  git st
 8386  commit 
 8387  push 

我把不相关的东西包括在这个列表中，这样我就不会意外地删掉一些相关的东西；正如你所看到的，所有这些历史都是连续的。以下是我历史上提到1601年的一切：

$ history | grep 1601
 1601  npm run test
 8363  git co -b 1601
 8381      git push --set-upstream origin 1601
 8438  git co 1601
 8445  git co 1601
 8446  git show-ref 1601
 8447  history | grep 1601
 8449  git show-ref | grep 1601
 8458  git show-ref --heads --tags | grep 1601
 8460  history | grep 1601
 8461  history | grep (1601|merge)
 8462  history | grep -p (1601|merge)
 8464  history | grep -E (1601|merge)
 8466  history | grep -E -e (1601|merge)
 8467  history | grep -E -e \(1601|merge\)
 8468  history | grep -E -e '(1601|merge)'
 8469  history | grep -E -e '(1601|merge|master)'
 8470  history | grep -E -e '(1601|1601|merge|master)'
 8472  history | grep -E -e '(1601|1601|merge|master)'
 8474  history | grep -E -e '(1601|1601|merge|master)'
 8480  history | grep 1601

$ git co 1601
warning: refname '1601' is ambiguous.
Already on '1601'
Your branch is up to date with 'origin/1601'.

null

$ git show-ref | grep 1601
137b74c8ff6807f07bb32ba0d2f76a3ba287e981 refs/heads/1601
137b74c8ff6807f07bb32ba0d2f76a3ba287e981 refs/remotes/origin/1601

$ git tag -l

$ git show-ref --heads --tags | grep 1601
137b74c8ff6807f07bb32ba0d2f76a3ba287e981 refs/heads/1601

cat .git/config
# this is the only place where it mentions 1601
[branch "1601"]
        remote = origin
        merge = refs/heads/1601

$ cat .git/config | grep 1601
[branch "1601"]
        merge = refs/heads/1601

$ git checkout 1601 --
warning: refname '1601' is ambiguous.
Already on '1601'
Your branch is up to date with 'origin/1601'.

$ git ls-remote . \*1601*
beea6ee68d6fe6b4f5222c0efe0e206e23af993c        refs/heads/1601
beea6ee68d6fe6b4f5222c0efe0e206e23af993c        refs/remotes/origin/1601

$ git show 1601 # this only shows one log message
warning: refname '1601' is ambiguous.
commit beea6ee68d6fe6b4f5222c0efe0e206e23af993c (HEAD -> 1601, origin/1601)
...

$ git --version
git version 2.31.1

$ type git
git is hashed (/usr/bin/git)

为什么我会得到这个警告，我如何摆脱它，我如何在未来预防它？

Answer 1

我可以通过给一个分支一个与提交的SHA1前缀匹配的名称来获得这个行为。

$ git rev-list @ | egrep '^[0-9]{4}'
7802d6937673dbff4d26dc906c714a054c9e883e
81070af68e1b254c7f36eccb1261050a5a4a133a
7537dac08fd165845b6300f32c19a52fc7fa7299
$ git branch 7802
$ git branch 9999
$ git checkout 7802
warning: refname '7802' is ambiguous.
Switched to branch '7802'
$ git checkout 9999
Switched to branch '9999'
$