Fix rewriting issue references with group milestones

1 files changed, 5 insertions, 3 deletions

diff --git a/app/models/milestone.rb b/app/models/milestone.rb
index a3070a12b7c..47e6b785c39 100644
--- a/app/models/milestone.rb
+++ b/app/models/milestone.rb
@@ -162,9 +162,7 @@ class Milestone < ActiveRecord::Base
   #   Milestone.first.to_reference(cross_namespace_project)  # => "gitlab-org/gitlab-ce%1"
   #   Milestone.first.to_reference(same_namespace_project)   # => "gitlab-ce%1"
   #
-  def to_reference(from_project = nil, format: :iid, full: false)
-    return if group_milestone? && format != :name
-
+  def to_reference(from_project = nil, format: :name, full: false)
     format_reference = milestone_format_reference(format)
     reference = "#{self.class.reference_prefix}#{format_reference}"
 
@@ -241,6 +239,10 @@ class Milestone < ActiveRecord::Base
   def milestone_format_reference(format = :iid)
     raise ArgumentError, 'Unknown format' unless [:iid, :name].include?(format)
 
+    if group_milestone? && format == :iid
+      raise ArgumentError, 'Cannot refer to a group milestone by an internal id!'
+    end
+
     if format == :name && !name.include?('"')
       %("#{name}")
     else