AWS: codecommit set default_branch only if defined

Do not try to update or reaad the AWS codecommit repository default branch if
the resource definition does not set it or is an empty string.

Fixes #5641

builtin/providers/aws/resource_aws_codecommit_repository.go

@@ -104,7 +104,7 @@ func resourceAwsCodeCommitRepositoryCreate(d *schema.ResourceData, meta interfac
 func resourceAwsCodeCommitRepositoryUpdate(d *schema.ResourceData, meta interface{}) error {
 	conn := meta.(*AWSClient).codecommitconn
 
-	if d.HasChange("default_branch") {
+	if d.HasChange("default_branch") && len(d.Get("default_branch").(string)) > 0 {
 		if err := resourceAwsCodeCommitUpdateDefaultBranch(conn, d); err != nil {
 			return err
 		}
@@ -135,7 +135,7 @@ func resourceAwsCodeCommitRepositoryRead(d *schema.ResourceData, meta interface{
 	d.Set("arn", *out.RepositoryMetadata.Arn)
 	d.Set("clone_url_http", *out.RepositoryMetadata.CloneUrlHttp)
 	d.Set("clone_url_ssh", *out.RepositoryMetadata.CloneUrlSsh)
-	if out.RepositoryMetadata.DefaultBranch != nil {
+	if out.RepositoryMetadata.DefaultBranch != nil && len(d.Get("default_branch").(string)) > 0 {
 		d.Set("default_branch", *out.RepositoryMetadata.DefaultBranch)
 	}