Add frontend "keep divergent refs" option

app/assets/javascripts/mirrors/mirror_repos.js

@@ -22,15 +22,18 @@ export default class MirrorRepos {
   }
 
   initMirrorPush() {
+    this.$keepDivergentRefsInput = $('.js-mirror-keep-divergent-refs', this.$form);
     this.$passwordGroup = $('.js-password-group', this.$container);
     this.$password = $('.js-password', this.$passwordGroup);
     this.$authMethod = $('.js-auth-method', this.$form);
 
+    this.$keepDivergentRefsInput.on('change', () => this.updateKeepDivergentRefs());
     this.$authMethod.on('change', () => this.togglePassword());
     this.$password.on('input.updateUrl', () => this.debouncedUpdateUrl());
 
     this.initMirrorSSH();
     this.updateProtectedBranches();
+    this.updateKeepDivergentRefs();
   }
 
   initMirrorSSH() {
@@ -61,6 +64,16 @@ export default class MirrorRepos {
     $('.js-mirror-protected-hidden', this.$form).val(val);
   }
 
+  updateKeepDivergentRefs() {
+    const field = this.$keepDivergentRefsInput.get(0);
+
+    // This field only exists after the form is switched to 'Push' mode
+    if (field) {
+      const val = field.checked ? this.$keepDivergentRefsInput.val() : '0';
+      $('.js-mirror-keep-divergent-refs-hidden', this.$form).val(val);
+    }
+  }
+
   registerUpdateListeners() {
     this.debouncedUpdateUrl = debounce(() => this.updateUrl(), 200);
     this.$urlInput.on('input', () => this.debouncedUpdateUrl());

app/controllers/projects/mirrors_controller.rb

@@ -77,6 +77,7 @@ class Projects::MirrorsController < Projects::ApplicationController
         id
         enabled
         only_protected_branches
+        keep_divergent_refs
         auth_method
         password
         ssh_known_hosts

app/views/projects/mirrors/_mirror_repos_push.html.haml

 - protocols = Gitlab::UrlSanitizer::ALLOWED_SCHEMES.join('|')
+- keep_divergent_refs = Feature.enabled?(:keep_divergent_refs, @project)
 
 = f.fields_for :remote_mirrors, @project.remote_mirrors.build do |rm_f|
   = rm_f.hidden_field :enabled, value: '1'
   = rm_f.hidden_field :url, class: 'js-mirror-url-hidden', required: true, pattern: "(#{protocols}):\/\/.+"
   = rm_f.hidden_field :only_protected_branches, class: 'js-mirror-protected-hidden'
+  - if keep_divergent_refs
+    = rm_f.hidden_field :keep_divergent_refs, class: 'js-mirror-keep-divergent-refs-hidden'
   = render partial: 'projects/mirrors/ssh_host_keys', locals: { f: rm_f }
   = render partial: 'projects/mirrors/authentication_method', locals: { f: rm_f }
+  - if keep_divergent_refs
+    .form-check.append-bottom-10
+      = check_box_tag :keep_divergent_refs, '1', false, class: 'js-mirror-keep-divergent-refs form-check-input'
+      = label_tag :keep_divergent_refs, 'Keep divergent refs', class: 'form-check-label'