Fix "Reload with full diff" URL button in compare branch view

This button worked when viewing merge requests because the JavaScript
stripped the .html in the Ajax request. However, it left the .html suffix
in the compare branch view.

CHANGELOG

 Please view this file on the master branch, on stable branches it's out of date.
 
 v 8.0.0 (unreleased)
+  - Fix "Reload with full diff" URL button in compare branch view (Stan Hu)
   - Remove user OAuth tokens from the database and request new tokens each session (Stan Hu)
   - Only show recent push event if the branch still exists or a recent merge request has not been created (Stan Hu)
   - Remove satellites

app/views/projects/diffs/_warning.html.haml

@@ -3,7 +3,7 @@
     Too many changes to show.
     .pull-right
       - unless diff_hard_limit_enabled?
-        = link_to "Reload with full diff", url_for(params.merge(force_show_diff: true, format: :html)), class: "btn btn-sm btn-warning"
+        = link_to "Reload with full diff", url_for(params.merge(force_show_diff: true, format: nil)), class: "btn btn-sm btn-warning"
 
       - if current_controller?(:commit) or current_controller?(:merge_requests)
         - if current_controller?(:commit)

features/project/commits/commits.feature

@@ -41,6 +41,7 @@ Feature: Project Commits
   Scenario: I browse big commit
     Given I visit big commit page
     Then I see big commit warning
+    And I see "Reload with full diff" link
 
   Scenario: I browse a commit with an image
     Given I visit a commit with an image that changed

features/steps/project/commits/commits.rb

@@ -79,6 +79,12 @@ class Spinach::Features::ProjectCommits < Spinach::FeatureSteps
     expect(page).to have_content "Too many changes"
   end
 
+  step 'I see "Reload with full diff" link' do
+    link = find_link('Reload with full diff')
+    expect(link[:href]).to end_with('?force_show_diff=true')
+    expect(link[:href]).not_to include('.html')
+  end
+
   step 'I visit a commit with an image that changed' do
     visit namespace_project_commit_path(@project.namespace, @project, sample_image_commit.id)
   end