Option to set default branch at repository creation (#10803)

* Option to set default branch at repository creation
* Handle template repos with non-default master branch
* Add DefaultBranch handling on creation to API

Fix #9542

Signed-off-by: Andrew Thornton <art27@cantab.net>

routers/api/v1/repo/repo.go

@@ -218,14 +218,15 @@ func CreateUserRepo(ctx *context.APIContext, owner *models.User, opt api.CreateR
 		opt.Readme = "Default"
 	}
 	repo, err := repo_service.CreateRepository(ctx.User, owner, models.CreateRepoOptions{
-		Name:        opt.Name,
-		Description: opt.Description,
-		IssueLabels: opt.IssueLabels,
-		Gitignores:  opt.Gitignores,
-		License:     opt.License,
-		Readme:      opt.Readme,
-		IsPrivate:   opt.Private,
-		AutoInit:    opt.AutoInit,
+		Name:          opt.Name,
+		Description:   opt.Description,
+		IssueLabels:   opt.IssueLabels,
+		Gitignores:    opt.Gitignores,
+		License:       opt.License,
+		Readme:        opt.Readme,
+		IsPrivate:     opt.Private,
+		AutoInit:      opt.AutoInit,
+		DefaultBranch: opt.DefaultBranch,
 	})
 	if err != nil {
 		if models.IsErrRepoAlreadyExist(err) {