1 files changed, 14 insertions, 5 deletions

diff --git a/services/pull/merge.go b/services/pull/merge.go
index b430a9080e..7a19649327 100644
--- a/services/pull/merge.go
+++ b/services/pull/merge.go
@@ -209,18 +209,23 @@ func rawMerge(pr *models.PullRequest, doer *models.User, mergeStyle models.Merge
 	outbuf.Reset()
 	errbuf.Reset()
 
+	sig := doer.NewGitSig()
+	committer := sig
+
 	// Determine if we should sign
 	signArg := ""
 	if git.CheckGitVersionConstraint(">= 1.7.9") == nil {
-		sign, keyID, _ := pr.SignMerge(doer, tmpBasePath, "HEAD", trackingBranch)
+		sign, keyID, signer, _ := pr.SignMerge(doer, tmpBasePath, "HEAD", trackingBranch)
 		if sign {
 			signArg = "-S" + keyID
+			if pr.BaseRepo.GetTrustModel() == models.CommitterTrustModel || pr.BaseRepo.GetTrustModel() == models.CollaboratorCommitterTrustModel {
+				committer = signer
+			}
 		} else if git.CheckGitVersionConstraint(">= 2.0.0") == nil {
 			signArg = "--no-gpg-sign"
 		}
 	}
 
-	sig := doer.NewGitSig()
 	commitTimeStr := time.Now().Format(time.RFC3339)
 
 	// Because this may call hooks we should pass in the environment
@@ -228,8 +233,8 @@ func rawMerge(pr *models.PullRequest, doer *models.User, mergeStyle models.Merge
 		"GIT_AUTHOR_NAME="+sig.Name,
 		"GIT_AUTHOR_EMAIL="+sig.Email,
 		"GIT_AUTHOR_DATE="+commitTimeStr,
-		"GIT_COMMITTER_NAME="+sig.Name,
-		"GIT_COMMITTER_EMAIL="+sig.Email,
+		"GIT_COMMITTER_NAME="+committer.Name,
+		"GIT_COMMITTER_EMAIL="+committer.Email,
 		"GIT_COMMITTER_DATE="+commitTimeStr,
 	)
 
@@ -346,6 +351,10 @@ func rawMerge(pr *models.PullRequest, doer *models.User, mergeStyle models.Merge
 				return "", fmt.Errorf("git commit [%s:%s -> %s:%s]: %v\n%s\n%s", pr.HeadRepo.FullName(), pr.HeadBranch, pr.BaseRepo.FullName(), pr.BaseBranch, err, outbuf.String(), errbuf.String())
 			}
 		} else {
+			if committer != sig {
+				// add trailer
+				message += fmt.Sprintf("\nCo-Authored-By: %s\nCo-Committed-By: %s\n", sig.String(), sig.String())
+			}
 			if err := git.NewCommand("commit", signArg, fmt.Sprintf("--author='%s <%s>'", sig.Name, sig.Email), "-m", message).RunInDirTimeoutEnvPipeline(env, -1, tmpBasePath, &outbuf, &errbuf); err != nil {
 				log.Error("git commit [%s:%s -> %s:%s]: %v\n%s\n%s", pr.HeadRepo.FullName(), pr.HeadBranch, pr.BaseRepo.FullName(), pr.BaseBranch, err, outbuf.String(), errbuf.String())
 				return "", fmt.Errorf("git commit [%s:%s -> %s:%s]: %v\n%s\n%s", pr.HeadRepo.FullName(), pr.HeadBranch, pr.BaseRepo.FullName(), pr.BaseBranch, err, outbuf.String(), errbuf.String())
@@ -526,7 +535,7 @@ func IsSignedIfRequired(pr *models.PullRequest, doer *models.User) (bool, error)
 		return true, nil
 	}
 
-	sign, _, err := pr.SignMerge(doer, pr.BaseRepo.RepoPath(), pr.BaseBranch, pr.GetGitRefName())
+	sign, _, _, err := pr.SignMerge(doer, pr.BaseRepo.RepoPath(), pr.BaseBranch, pr.GetGitRefName())
 
 	return sign, err
 }