Remove an undeeded space concatenation from `wpmu_validate_user_signup()`.

This was previously used to prevent `strpos()` returning 0, which is not needed after r32942.
See #32444

Built from https://develop.svn.wordpress.org/trunk@32950


git-svn-id: http://core.svn.wordpress.org/trunk@32921 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/ms-functions.php

@@ -494,7 +494,7 @@ function wpmu_validate_user_signup($user_name, $user_email) {
 	if ( strlen( $user_name ) < 4 )
 		$errors->add('user_name',  __( 'Username must be at least 4 characters.' ) );
 
-	if ( strpos( ' ' . $user_name, '_' ) !== false )
+	if ( strpos( $user_name, '_' ) !== false )
 		$errors->add( 'user_name', __( 'Sorry, usernames may not contain the character &#8220;_&#8221;!' ) );
 
 	// all numeric?

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.3-alpha-32949';
+$wp_version = '4.3-alpha-32950';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.