[webui] Drop validation of user's email address

Cherry-picked from 1c264f59

src/api/app/models/user.rb

@@ -355,7 +355,7 @@ class User < ActiveRecord::Base
     errors.add(:password_hash_type, 'cannot be changed unless a new password has been provided.')
   end
 
-  validates :login, :email, :password, :password_hash_type, :state,
+  validates :login, :password, :password_hash_type, :state,
             presence: { message: 'must be given' }
 
   validates :login,
@@ -376,7 +376,8 @@ class User < ActiveRecord::Base
   # to confirm their registration.
   validates :email,
             format: { with:    %r{\A([\w\-\.\#\$%&!?*\'\+=(){}|~]+)@([0-9a-zA-Z\-\.\#\$%&!?*\'=(){}|~]+)+\z},
-                      message: 'must be a valid email address.' }
+                      message: 'must be a valid email address.',
+                      allow_blank: true }
 
   # We want to validate the format of the password and only allow alphanumeric
   # and some punctiation characters.

src/api/spec/models/user_spec.rb

@@ -10,7 +10,6 @@ RSpec.describe User do
     it { is_expected.to validate_length_of(:login).is_at_least(2).with_message('must have more than two characters.') }
     it { is_expected.to validate_length_of(:login).is_at_most(100).with_message('must have less than 100 characters.') }
 
-    it { is_expected.to validate_presence_of(:email).with_message('must be given') }
     it { is_expected.to allow_value('king@opensuse.org').for(:email) }
     it { is_expected.to_not allow_values('king.opensuse.org', 'opensuse.org', 'opensuse').for(:email) }