Make retarget optional, keep default behaviour without option

Author: kvaster

modules/setting/repository.go

@@ -84,6 +84,7 @@ var (
 			PopulateSquashCommentWithCommitMessages  bool
 			AddCoCommitterTrailers                   bool
 			TestConflictingPatchesWithGitApply       bool
+			RetargetChildsOnClose                    bool
 		} `ini:"repository.pull-request"`
 
 		// Issue Setting
@@ -207,6 +208,7 @@ var (
 			PopulateSquashCommentWithCommitMessages  bool
 			AddCoCommitterTrailers                   bool
 			TestConflictingPatchesWithGitApply       bool
+			RetargetChildsOnClose                    bool
 		}{
 			WorkInProgressPrefixes: []string{"WIP:", "[WIP]"},
 			// Same as GitHub. See

routers/api/v1/repo/pull.go

@@ -904,7 +904,7 @@ func MergePullRequest(ctx *context.APIContext) {
 			}
 			defer headRepo.Close()
 		}
-		if pr.BaseRepoID == pr.HeadRepoID {
+		if setting.Repository.PullRequest.RetargetChildsOnClose && pr.BaseRepoID == pr.HeadRepoID {
 			if err := pull_service.RebaseBranchPulls(ctx, ctx.Doer, pr.HeadRepoID, pr.HeadBranch, pr.BaseBranch); err != nil {
 				log.Error("RebaseBranchPulls: %v", err)
 				ctx.Error(http.StatusInternalServerError, "RebaseBranchPulls", err)

routers/web/repo/pull.go

@@ -1400,7 +1400,7 @@ func CleanUpPullRequest(ctx *context.Context) {
 func deleteBranch(ctx *context.Context, pr *issues_model.PullRequest, gitRepo *git.Repository) {
 	fullBranchName := pr.HeadRepo.FullName() + ":" + pr.HeadBranch
 
-	if pr.BaseRepoID == pr.HeadRepoID {
+	if setting.Repository.PullRequest.RetargetChildsOnClose && pr.BaseRepoID == pr.HeadRepoID {
 		if err := pull_service.RebaseBranchPulls(ctx, ctx.Doer, pr.HeadRepoID, pr.HeadBranch, pr.BaseBranch); err != nil {
 			log.Error("RebaseBranchPulls: %v", err)
 			ctx.Flash.Error(ctx.Tr("repo.branch.deletion_failed", fullBranchName))