Add new setting for the default initial branch name

app/views/admin/application_settings/_initial_branch_name.html.haml

+= form_for @application_setting, url: general_admin_application_settings_path(anchor: 'js-default-branch-name'), html: { class: 'fieldset-form' } do |f|
+  = form_errors(@application_setting)
+
+  - fallback_branch_name = '<code>master</code>'
+
+  %fieldset
+    .form-group
+      = f.label :default_branch_name, _('Default initial branch name'), class: 'label-light'
+      = f.text_field :default_branch_name, placeholder: 'master', class: 'form-control'
+      %span.form-text.text-muted
+        = (_("Changes affect new repositories only. If not specified, Git's default name %{branch_name_default} will be used.") % { branch_name_default: fallback_branch_name } ).html_safe
+  = f.submit _('Save changes'), class: 'gl-button btn-success'

app/views/admin/application_settings/repository.html.haml

@@ -2,6 +2,18 @@
 - page_title _("Repository")
 - @content_class = "limit-container-width" unless fluid_layout
 
+- if Feature.enabled?(:global_default_branch_name)
+  %section.settings.as-default-branch-name.no-animate#js-default-branch-name{ class: ('expanded' if expanded_by_default?) }
+    .settings-header
+      %h4
+        = _('Default initial branch name')
+      %button.gl-button.js-settings-toggle{ type: 'button' }
+        = expanded_by_default? ? _('Collapse') : _('Expand')
+      %p
+        = _('Set the default name of the initial branch when creating new repositories through the user interface.')
+    .settings-content
+      = render 'initial_branch_name'
+
 %section.settings.as-mirror.no-animate#js-mirror-settings{ class: ('expanded' if expanded_by_default?) }
   .settings-header
     %h4

locale/gitlab.pot

@@ -4260,6 +4260,9 @@ msgstr ""
 msgid "Changes"
 msgstr ""
 
+msgid "Changes affect new repositories only. If not specified, Git's default name %{branch_name_default} will be used."
+msgstr ""
+
 msgid "Changes are shown as if the <b>source</b> revision was being merged into the <b>target</b> revision."
 msgstr ""
 
@@ -7405,6 +7408,9 @@ msgstr ""
 msgid "Default first day of the week in calendars and date pickers."
 msgstr ""
 
+msgid "Default initial branch name"
+msgstr ""
+
 msgid "Default issue template"
 msgstr ""
 
@@ -21068,6 +21074,9 @@ msgstr ""
 msgid "Set the default expiration time for each job's artifacts. 0 for unlimited. The default unit is in seconds, but you can define an alternative. For example: <code>4 mins 2 sec</code>, <code>2h42min</code>."
 msgstr ""
 
+msgid "Set the default name of the initial branch when creating new repositories through the user interface."
+msgstr ""
+
 msgid "Set the due date to %{due_date}."
 msgstr ""