Index: modules/user/user.test
===================================================================
RCS file: /cvs/drupal/drupal/modules/user/user.test,v
retrieving revision 1.111
diff -u -r1.111 user.test
--- modules/user/user.test	18 Dec 2010 00:56:18 -0000	1.111
+++ modules/user/user.test	4 Jan 2011 21:35:57 -0000
@@ -103,6 +103,31 @@
     $this->drupalPost('user/login', $auth, t('Log in'));
     $this->assertText(t('Member for'), t('User can log in after administrator approval.'));
   }
+  
+  function testRegistrationEmailDuplicates() {
+    // Don't require e-mail verification.
+    variable_set('user_email_verification', FALSE);
+
+    // Allow registration by site visitors without administrator approval.
+    variable_set('user_register', USER_REGISTER_VISITORS);
+
+    // Set up a user to check for duplicates.
+    $duplicate_user = $this->drupalCreateUser();
+
+    $edit = array();
+    $edit['name'] = $this->randomName();
+    $edit['mail'] = $duplicate_user->mail;
+
+    // Attempt to create a new account using an existing e-mail address.
+    $this->drupalPost('user/register', $edit, t('Create new account'));
+    $this->assertText(t('The e-mail address @email is already registered.', array('@email' => $duplicate_user->mail)), t('Supplying an exact duplicate email address displays an error message'));
+
+    // Attempt to bypass duplicate email registration validation by adding spaces.
+    $edit['mail'] = $mail = '   ' . $duplicate_user->mail . '   ';
+
+    $this->drupalPost('user/register', $edit, t('Create new account'));
+    $this->assertText(t('The e-mail address @email is already registered.', array('@email' => $mail)), t('Supplying a duplicate email address with added whitespace displays an error message'));
+  }
 
   function testRegistrationDefaultValues() {
     // Allow registration by site visitors without administrator approval.
Index: modules/user/user.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/user/user.module,v
retrieving revision 1.1229
diff -u -r1.1229 user.module
--- modules/user/user.module	28 Dec 2010 21:46:23 -0000	1.1229
+++ modules/user/user.module	4 Jan 2011 21:35:56 -0000
@@ -1207,7 +1207,7 @@
     if ($error = user_validate_mail($form_state['values']['mail'])) {
       form_set_error('mail', $error);
     }
-    elseif ((bool) db_select('users')->fields('users', array('uid'))->condition('uid', $account->uid, '<>')->condition('mail', db_like($form_state['values']['mail']), 'LIKE')->range(0, 1)->execute()->fetchField()) {
+    elseif ((bool) db_select('users')->fields('users', array('uid'))->condition('uid', $account->uid, '<>')->condition('mail', db_like(trim($form_state['values']['mail'])), 'LIKE')->range(0, 1)->execute()->fetchField()) {
       // Format error message dependent on whether the user is logged in or not.
       if ($GLOBALS['user']->uid) {
         form_set_error('mail', t('The e-mail address %email is already taken.', array('%email' => $form_state['values']['mail'])));