Fixes #3167: Active Google channels cause Email channels to loose email addresses.

app/models/channel.rb

@@ -346,7 +346,15 @@ get instance of channel driver
     options[:inbound][:options][:password]  = result[:access_token]
     options[:outbound][:options][:password] = result[:access_token]
 
-    save!
+    return if new_record?
+
+    # ATTENTION: We don't want to execute any other callbacks here
+    # because `after_initialize` leaks the current scope of the Channel class
+    # as described here: https://api.rubyonrails.org/classes/ActiveRecord/Relation.html#method-i-new
+    # which leads to unexpected effects like:
+    # Channel.where(area: 'Google::Account').limit(1).find_each { |c| puts Channel.all.to_sql }
+    # => "SELECT "channels".* FROM "channels" WHERE "channels"."area" = 'Google::Account'"
+    update_column(:options, options) # rubocop:disable Rails/SkipsModelValidations
   rescue => e
     logger.error e
     raise "Failed to refresh XOAUTH2 access_token of provider '#{options[:auth][:provider]}'! #{e.inspect}"

spec/requests/integration/gmail_spec.rb

@@ -62,4 +62,17 @@ RSpec.describe 'Gmail XOAUTH2' do # rubocop:disable RSpec/DescribeClass
       expect(result[:result]).to eq('ok')
     end
   end
+
+  context 'when non-Google channels are present' do
+
+    let!(:email_address) { create(:email_address, channel: create(:channel, area: 'Some::Other')) }
+
+    before do
+      channel
+    end
+
+    it "doesn't remove email address assignments" do
+      expect { Channel.where(area: 'Google::Account').find_each {} }.not_to change { email_address.reload.channel_id }
+    end
+  end
 end