Fix issue #6847

app/controllers/users_controller.rb

@@ -61,6 +61,8 @@ def update
             flash[:notice] = I18n.t 'users.update.unconfirmed_email_changed'
           end
         else
+          # if this field is not cleared, the form will render as though the change were successful
+          @user.unconfirmed_email = nil
           flash[:error] = I18n.t 'users.update.unconfirmed_email_not_changed'
         end
       elsif u[:auto_follow_back]

app/models/user.rb

@@ -32,6 +32,8 @@ class User < ActiveRecord::Base
   validates :color_theme, inclusion: {in: AVAILABLE_COLOR_THEME_CODES}, allow_blank: true
   validates_format_of :unconfirmed_email, :with  => Devise.email_regexp, :allow_blank => true
 
+  validate :unconfirmed_email_quasiuniqueness
+
   validates_presence_of :person, :unless => proc {|user| user.invitation_token.present?}
   validates_associated :person
   validate :no_person_with_same_username
@@ -83,6 +85,8 @@ class User < ActiveRecord::Base
 
   before_save :guard_unconfirmed_email
 
+  after_save :remove_invalid_unconfirmed_emails
+
   def self.all_sharing_with_person(person)
     User.joins(:contacts).where(:contacts => {:person_id => person.id})
   end
@@ -484,6 +488,13 @@ def mine?(target)
   end
 
 
+  # Ensure that the unconfirmed email isn't already someone's email
+  def unconfirmed_email_quasiuniqueness
+    if User.exists?(["id != ? AND email = ?", id, unconfirmed_email])
+      errors.add(:unconfirmed_email, "is already in use")
+    end
+  end
+
   def guard_unconfirmed_email
     self.unconfirmed_email = nil if unconfirmed_email.blank? || unconfirmed_email == email
 
@@ -492,6 +503,16 @@ def guard_unconfirmed_email
     end
   end
 
+  # Whenever email is set, clear all unconfirmed emails which match
+  def remove_invalid_unconfirmed_emails
+    if email_changed?
+      User.where("unconfirmed_email = ?", email).find_each do |problem_user|
+        problem_user.unconfirmed_email = nil
+        problem_user.save
+      end
+    end
+  end
+
   # Generate public/private keys for User and associated Person
   def generate_keys
     key_size = (Rails.env == 'test' ? 512 : 4096)

spec/models/user_spec.rb

@@ -305,6 +305,13 @@
         alice.email = "somebody@anywhere"
         expect(alice).not_to be_valid
       end
+
+      it "resets a matching unconfirmed_email on save" do
+        eve.update_attribute :unconfirmed_email, "new@email.com"
+        alice.update_attribute :email, "new@email.com"
+        eve.reload
+        expect(eve.unconfirmed_email).to eql(nil)
+      end
     end
 
     describe "of unconfirmed_email" do
@@ -321,6 +328,11 @@
         expect(alice).to be_valid
       end
 
+      it "requires an unconfirmed_email address which is not another user's email address" do
+        alice.unconfirmed_email = eve.email
+        expect(alice).not_to be_valid
+      end
+
       it "requires a valid unconfirmed_email address" do
         alice.unconfirmed_email = "somebody@anywhere"
         expect(alice).not_to be_valid