Use Web IDE path for merge request edit buttons

app/helpers/blob_helper.rb

@@ -37,7 +37,7 @@ module BlobHelper
   end
 
   def ide_edit_button(project = @project, ref = @ref, path = @path, options = {})
-    return unless Feature.enabled?(:web_ide_default)
+    return if Feature.enabled?(:web_ide_default)
     return unless blob = readable_blob(options, path, project, ref)
 
     edit_button_tag(blob,

app/serializers/diff_file_base_entity.rb

@@ -27,9 +27,13 @@ class DiffFileBaseEntity < Grape::Entity
 
     next unless merge_request.source_project
 
-    project_edit_blob_path(merge_request.source_project,
-      tree_join(merge_request.source_branch, diff_file.new_path),
-      options)
+    if Feature.enabled?(:web_ide_default)
+      ide_edit_path(merge_request.source_project, merge_request.source_branch, diff_file.new_path)
+    else
+      project_edit_blob_path(merge_request.source_project,
+        tree_join(merge_request.source_branch, diff_file.new_path),
+        options)
+    end
   end
 
   expose :old_path_html do |diff_file|

spec/features/merge_request/maintainer_edits_fork_spec.rb

@@ -18,6 +18,8 @@ describe 'a maintainer edits files on a source-branch of an MR from a fork', :js
   end
 
   before do
+    stub_feature_flags(web_ide_default: false)
+
     target_project.add_maintainer(user)
     sign_in(user)