add some comments

Co-authored-by: wxiaoguang <[email protected]>

Author: 2 people

routers/private/hook_verification.go

@@ -30,6 +30,9 @@ func verifyCommits(oldCommitID, newCommitID string, repo *git.Repository, env []
 
 	var command *git.Command
 	if oldCommitID == git.EmptySHA {
+		// When creating a new branch, the oldCommitID is empty, by using "newCommitID --not --all":
+		// List commits that are reachable by following the newCommitID, exclude "all" existing heads/tags commits
+		// So, it only lists the new commits received, doesn't list the commits already present in the receiving repository
 		command = git.NewCommand(repo.Ctx, "rev-list").AddDynamicArguments(newCommitID).AddArguments("--not", "--all")
 	} else {
 		command = git.NewCommand(repo.Ctx, "rev-list").AddDynamicArguments(oldCommitID + "..." + newCommitID)