Merge branch 'master' into glitch-soc/merge-upstream

Manually-resolved conflicts:
	.circleci/config.yml
	app/controllers/accounts_controller.rb
	app/controllers/auth/passwords_controller.rb
	app/controllers/statuses_controller.rb
	app/javascript/packs/public.js
	app/models/media_attachment.rb
	app/views/stream_entries/_content_spoiler.html.haml
	app/views/stream_entries/_media.html.haml
	config/locales/en.yml
	config/locales/ja.yml
	config/locales/pl.yml
	lib/mastodon/version.rb

Some content from app/javascript/packs/public.js has been split to
app/javascript/core/settings.js.

Translation strings for glitch-soc's keyword mutes were dropped.

Everything else was mostly “take both”.

spec/controllers/about_controller_spec.rb

@@ -8,10 +8,6 @@ RSpec.describe AboutController, type: :controller do
       get :show
     end
 
-    it 'assigns @body_classes' do
-      expect(assigns(:body_classes)).to eq 'about-body'
-    end
-
     it 'assigns @instance_presenter' do
       expect(assigns(:instance_presenter)).to be_kind_of InstancePresenter
     end
@@ -26,10 +22,6 @@ RSpec.describe AboutController, type: :controller do
       get :more
     end
 
-    it 'assigns @body_classes' do
-      expect(assigns(:body_classes)).to eq 'about-body'
-    end
-
     it 'assigns @instance_presenter' do
       expect(assigns(:instance_presenter)).to be_kind_of InstancePresenter
     end
@@ -44,10 +36,6 @@ RSpec.describe AboutController, type: :controller do
       get :terms
     end
 
-    it 'assigns @body_classes' do
-      expect(assigns(:body_classes)).to eq 'about-body'
-    end
-
     it 'returns http success' do
       expect(response).to have_http_status(200)
     end

spec/models/account_spec.rb

@@ -618,10 +618,10 @@ RSpec.describe Account, type: :model do
         expect(account).not_to model_have_error_on_field(:username)
       end
 
-      it 'is valid even if the username doesn\'t only contains letters, numbers and underscores' do
+      it 'is invalid if the username doesn\'t only contains letters, numbers and underscores' do
         account = Fabricate.build(:account, domain: 'domain', username: 'the-doctor')
         account.valid?
-        expect(account).not_to model_have_error_on_field(:username)
+        expect(account).to model_have_error_on_field(:username)
       end
 
       it 'is valid even if the username is longer then 30 characters' do

spec/views/stream_entries/show.html.haml_spec.rb

@@ -12,6 +12,7 @@ describe 'stream_entries/show.html.haml', without_verify_partial_doubles: true d
     allow(view).to receive(:full_asset_url).and_return('//asset.host/image.svg')
     allow(view).to receive(:local_time)
     allow(view).to receive(:local_time_ago)
+    assign(:instance_presenter, InstancePresenter.new)
   end
 
   it 'has valid author h-card and basic data for a detailed_status' do