嗯，我已经尝试了你认为你所做的，完全按照你写的去做
cd /tmp
mkdir so35588521
cd so35588521
git init
# Initialized empty Git repository in /tmp/so35588521/.git/
touch 1
echo "1" > 1
git add .
git commit -m "first"
# [master (root-commit) 173f431] first
# 1 file changed, 0 insertions(+), 0 deletions(-)
# create mode 100644 1
touch 2
touch 3
git add .
git commit -m "second"
# [master a9fdcc9] second
# 2 files changed, 0 insertions(+), 0 deletions(-)
# create mode 100644 2
# create mode 100644 3
git log
# commit a9fdcc9338c9b3de25c211580a35ab63d1d57c2e
# Author: Me and my email
# Date: Tue Feb 23 22:46:50 2016 +0100
git revert a9fd
# [master dd5a86e] Revert "second"
# 2 files changed, 0 insertions(+), 0 deletions(-)
# delete mode 100644 2
# delete mode 100644 3
如您所见 - 一切顺利。因此，我想，啊哈！她/他一定做了其他事情，而忽略了在 SO 上提及它。哦，好吧，无论如何，我会弄清楚她/他用我的水晶球做了什么。把它放在无用的地方有什么意义。
所以，合并，git 说。然后，让我们创建一个分支并尝试将它与我们的 master 分支合并。
git checkout -b a_branch
# Switched to a new branch 'a_branch'
echo "2" > 1
git status
# On branch a_branch ...
git add .
git commit -m "third"
# [a_branch 96d3a7a] third
# 1 file changed, 1 insertion(+), 1 deletion(-)
git checkout master
# Switched to branch 'master'
echo "3" > 1
git add .
git commit -m "fourth"
# [master 7f72eec] fourth
# 1 file changed, 2 insertions(+), 1 deletion(-)
#### Now we have first commit, and second, and revert second, and two commits: third on **a_branch** branch and fourth on **master**.
git merge a_branch
# Auto-merging 1
# CONFLICT (content): Merge conflict in 1
# Automatic merge failed; fix conflicts and then commit the result.
# *Oh DANG* whyy? Git stop, don't do that it hurts, revert!
git revert last_commit_id_from_git_log
# error: revert is not possible because you have unmerged files.
# hint: Fix them up in the work tree, and then use 'git add/rm <file>'
# hint: as appropriate to mark resolution and make a commit.
# fatal: revert failed
# *Git nope!*
现在，这只是我的猜测，我希望给 SO 带来一点幽默。如果这不是您所做的，您能否告诉我们您所做的确切步骤？由于我无法复制您遇到的错误，因此我感到无法解决问题。
编辑：
既然 OP 坚持肯定没有做分支...
rm *
rm -rf .git
git init
echo -e "line one\n" > 1
git add .
git ci -m "first"
echo -e "line two\n" >> 1
git ci -a -m "second"
git log
# commit 23d710610d98c1046844870557208f335e76a933
# Author: ME <me@home>
# Date: Tue Feb 23 23:31:28 2016 +0100
#
# second
#
# commit 22873fb5fbf06d80a1779fe6740060c660d68714
# Author: ME <me@home>
# Date: Tue Feb 23 23:30:47 2016 +0100
#
# first
git revert "first"
# fatal: bad revision 'first' # but OK i assume You used id, so,
git revert 22873fb5fbf06d80
# error: could not revert 22873fb... first
# hint: after resolving the conflicts, mark the corrected paths
# hint: with 'git add <paths>' or 'git rm <paths>'
# hint: and commit the result with 'git commit'
啊哈，现在我明白了！那……这很奇怪。
好的，我检查了，实际上你是对的，在我的 git --version 2.6.3 上，我可以复制这种行为。实际上，我认为你在这里进入了非常极端的情况。发生的事情是，在您的第二次提交之后，git 存储了您对文件 test.txt 所做的更改并保留了这些更改。现在你告诉他（它？）git revert first_commit_id 实际上创建了文件 test.txt。我不能确定，但这对我来说似乎是一个小错误。
但是！ 如果您在第二次提交中添加文件，例如 test2.txt（因此您将在 git 存储库中有两个文件版本化），那么 revert 可以工作。