Index: src/wp-includes/option.php
===================================================================
--- src/wp-includes/option.php	(revision 33008)
+++ src/wp-includes/option.php	(working copy)
@@ -54,7 +54,7 @@
 	if ( ! defined( 'WP_INSTALLING' ) ) {
 		// prevent non-existent options from triggering multiple queries
 		$notoptions = wp_cache_get( 'notoptions', 'options' );
-		if ( isset( $notoptions[ $option ] ) ) {
+		if ( array_key_exists( $option, $notoptions ) ) {
 			/**
 			 * Filter the default value for an option.
 			 *
@@ -70,7 +70,7 @@
 
 		$alloptions = wp_load_alloptions();
 
-		if ( isset( $alloptions[$option] ) ) {
+		if ( array_key_exists( $option, $alloptions ) ) {
 			$value = $alloptions[$option];
 		} else {
 			$value = wp_cache_get( $option, 'options' );
@@ -319,14 +319,14 @@
 		return false;
 
 	$notoptions = wp_cache_get( 'notoptions', 'options' );
-	if ( is_array( $notoptions ) && isset( $notoptions[$option] ) ) {
+	if ( is_array( $notoptions ) && array_key_exists( $option, $notoptions ) ) {
 		unset( $notoptions[$option] );
 		wp_cache_set( 'notoptions', $notoptions, 'options' );
 	}
 
 	if ( ! defined( 'WP_INSTALLING' ) ) {
 		$alloptions = wp_load_alloptions();
-		if ( isset( $alloptions[$option] ) ) {
+		if ( array_key_exists( $option, $alloptions ) ) {
 			$alloptions[ $option ] = $serialized_value;
 			wp_cache_set( 'alloptions', $alloptions, 'options' );
 		} else {
@@ -401,7 +401,7 @@
 
 	// Make sure the option doesn't already exist. We can check the 'notoptions' cache before we ask for a db query
 	$notoptions = wp_cache_get( 'notoptions', 'options' );
-	if ( !is_array( $notoptions ) || !isset( $notoptions[$option] ) )
+	if ( !is_array( $notoptions ) || !array_key_exists( $option, $notoptions ) )
 		/** This filter is documented in wp-includes/option.php */
 		if ( apply_filters( 'default_option_' . $option, false ) !== get_option( $option ) )
 			return false;
@@ -435,7 +435,7 @@
 
 	// This option exists now
 	$notoptions = wp_cache_get( 'notoptions', 'options' ); // yes, again... we need it to be fresh
-	if ( is_array( $notoptions ) && isset( $notoptions[$option] ) ) {
+	if ( is_array( $notoptions ) && array_key_exists( $option, $notoptions ) ) {
 		unset( $notoptions[$option] );
 		wp_cache_set( 'notoptions', $notoptions, 'options' );
 	}
@@ -502,7 +502,7 @@
 	if ( ! defined( 'WP_INSTALLING' ) ) {
 		if ( 'yes' == $row->autoload ) {
 			$alloptions = wp_load_alloptions();
-			if ( is_array( $alloptions ) && isset( $alloptions[$option] ) ) {
+			if ( is_array( $alloptions ) && array_key_exists( $option, $alloptions ) ) {
 				unset( $alloptions[$option] );
 				wp_cache_set( 'alloptions', $alloptions, 'options' );
 			}
@@ -620,7 +620,7 @@
 		if ( ! defined( 'WP_INSTALLING' ) ) {
 			// If option is not in alloptions, it is not autoloaded and thus has a timeout
 			$alloptions = wp_load_alloptions();
-			if ( !isset( $alloptions[$transient_option] ) ) {
+			if ( !array_key_exists( $transient_option, $alloptions ) ) {
 				$transient_timeout = '_transient_timeout_' . $transient;
 				if ( get_option( $transient_timeout ) < time() ) {
 					delete_option( $transient_option  );
@@ -800,7 +800,7 @@
 function get_user_setting( $name, $default = false ) {
 	$all_user_settings = get_all_user_settings();
 
-	return isset( $all_user_settings[$name] ) ? $all_user_settings[$name] : $default;
+	return array_key_exists( $name, $all_user_settings ) ) ? $all_user_settings[$name] : $default;
 }
 
 /**
@@ -847,7 +847,7 @@
 	$deleted = false;
 
 	foreach ( $names as $name ) {
-		if ( isset( $all_user_settings[$name] ) ) {
+		if ( array_key_exists( $name, $all_user_settings ) ) {
 			unset( $all_user_settings[$name] );
 			$deleted = true;
 		}
@@ -993,7 +993,7 @@
 	$notoptions_key = "{$wpdb->siteid}:notoptions";
 	$notoptions = wp_cache_get( $notoptions_key, 'site-options' );
 
-	if ( isset( $notoptions[$option] ) ) {
+	if ( array_key_exists( $option, $notoptions ) ) {
 
 		/**
 		 * Filter a specific default site option.
@@ -1093,7 +1093,7 @@
 
 		// Make sure the option doesn't already exist. We can check the 'notoptions' cache before we ask for a db query
 		$notoptions = wp_cache_get( $notoptions_key, 'site-options' );
-		if ( ! is_array( $notoptions ) || ! isset( $notoptions[$option] ) )
+		if ( ! is_array( $notoptions ) || ! array_key_exists( $option, $notoptions ) )
 			if ( false !== get_site_option( $option ) )
 				return false;
 
@@ -1109,7 +1109,7 @@
 
 		// This option exists now
 		$notoptions = wp_cache_get( $notoptions_key, 'site-options' ); // yes, again... we need it to be fresh
-		if ( is_array( $notoptions ) && isset( $notoptions[$option] ) ) {
+		if ( is_array( $notoptions ) && array_key_exists( $option, $notoptions ) ) {
 			unset( $notoptions[$option] );
 			wp_cache_set( $notoptions_key, $notoptions, 'site-options' );
 		}
@@ -1252,7 +1252,7 @@
 
 	$notoptions_key = "{$wpdb->siteid}:notoptions";
 	$notoptions = wp_cache_get( $notoptions_key, 'site-options' );
-	if ( is_array( $notoptions ) && isset( $notoptions[$option] ) ) {
+	if ( is_array( $notoptions ) && array_key_exists( $option, $notoptions ) ) {
 		unset( $notoptions[$option] );
 		wp_cache_set( $notoptions_key, $notoptions, 'site-options' );
 	}