Git合并行为（在x提交之前提前）

Question

我遇到过Git行为，我无法完全理解。回购被数十人使用。案件是这样的：

$ git checkout master
$ git merge --no-commit feature
Automatic merge went well; stopped before committing as requested

$ git status
On branch master
Your branch is up-to-date with 'origin/master'.

All conflicts fixed but you are still merging.
  (use "git commit" to conclude merge)

Changes to be committed:

    modified:   web/webapp/grails-app/views/layouts/empty.gsp

$ git commit -m 'commit message'
[master e6cc2eb] commit message

$ git status
On branch master
Your branch is ahead of 'origin/master' by 21 commits.
  (use "git push" to publish your local commits)

让我感到困惑的是这部分：

Your branch is ahead of 'origin/master' by 21 commits.

为什么它不是1？说清楚，那个empty.gsp文件只有一个变化。

实际上还有20个提交，但为什么它们在git status之后才显示？我可能会遗漏任何暗示吗？