Use Ruby 1.9 syntax in tab_single def and usage.

app/views/admin/appearances/preview.html.haml

-= render 'devise/shared/tab_single', { :tab_title => 'Sign in preview'  }
+= render 'devise/shared/tab_single', tab_title: 'Sign in preview'
 .login-box
   %form.show-gl-field-errors
     .form-group

app/views/devise/confirmations/new.html.haml

-= render 'devise/shared/tab_single', { :tab_title => 'Resend confirmation instructions' }
+= render 'devise/shared/tab_single', tab_title: 'Resend confirmation instructions'
 .login-box
   .login-body
     = form_for(resource, as: resource_name, url: confirmation_path(resource_name), html: { method: :post, class: 'show-gl-field-errors' }) do |f|

app/views/devise/passwords/edit.html.haml

-= render 'devise/shared/tab_single', { :tab_title => 'Change your password' }
+= render 'devise/shared/tab_single', tab_title:'Change your password'
 .login-box
   .login-body
     = form_for(resource, as: resource_name, url: password_path(resource_name), html: { method: :put, class: 'show-gl-field-errors' }) do |f|

app/views/devise/passwords/new.html.haml

-= render 'devise/shared/tab_single', { :tab_title => 'Reset Password' }
+= render 'devise/shared/tab_single', tab_title: 'Reset Password'
 .login-box
   .login-body
     = form_for(resource, as: resource_name, url: password_path(resource_name), html: { method: :post, class: 'show-gl-field-errors' }) do |f|

app/views/devise/sessions/two_factor.html.haml

@@ -3,7 +3,7 @@
     = page_specific_javascript_tag('u2f.js')
 
 %div
-  = render 'devise/shared/tab_single', { :tab_title => 'Two-Factor Authentication' }
+  = render 'devise/shared/tab_single', tab_title: 'Two-Factor Authentication'
   .login-box
     .login-body
       - if @user.two_factor_otp_enabled?

app/views/devise/shared/_tab_single.html.haml

-//  = render 'devise/shared/tab_single', :tab_title => 'Tab Title'
 %ul.nav-links.nav-tabs.new-session-tabs.single-tab
   %li.active
-    = link_to tab_title, '#', disabled: true
+    %a= tab_title

app/views/devise/unlocks/new.html.haml

-= render 'devise/shared/tab_single', { :tab_title => 'Resend unlock instructions' }
+= render 'devise/shared/tab_single', tab_title: 'Resend unlock instructions'
 .login-box
   .login-body
     = form_for(resource, as: resource_name, url: unlock_path(resource_name), html: { method: :post, class: 'show-gl-field-errors' }) do |f|