Index: wp-includes/functions.php
===================================================================
--- wp-includes/functions.php	(revision 23214)
+++ wp-includes/functions.php	(working copy)
@@ -2821,9 +2821,9 @@
 	// Allow plugin to filter the output error trigger
 	if ( WP_DEBUG && apply_filters( 'deprecated_function_trigger_error', true ) ) {
 		if ( ! is_null($replacement) )
-			trigger_error( sprintf( __('%1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.'), $function, $version, $replacement ) );
+			trigger_error( sprintf( __('%1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.'), $function, $version, $replacement ), _wp_debug_error_type() );
 		else
-			trigger_error( sprintf( __('%1$s is <strong>deprecated</strong> since version %2$s with no alternative available.'), $function, $version ) );
+			trigger_error( sprintf( __('%1$s is <strong>deprecated</strong> since version %2$s with no alternative available.'), $function, $version ), _wp_debug_error_type() );
 	}
 }
 
@@ -2861,9 +2861,9 @@
 	if ( WP_DEBUG && apply_filters( 'deprecated_file_trigger_error', true ) ) {
 		$message = empty( $message ) ? '' : ' ' . $message;
 		if ( ! is_null( $replacement ) )
-			trigger_error( sprintf( __('%1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.'), $file, $version, $replacement ) . $message );
+			trigger_error( sprintf( __('%1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.'), $file, $version, $replacement ) . $message, _wp_debug_error_type() );
 		else
-			trigger_error( sprintf( __('%1$s is <strong>deprecated</strong> since version %2$s with no alternative available.'), $file, $version ) . $message );
+			trigger_error( sprintf( __('%1$s is <strong>deprecated</strong> since version %2$s with no alternative available.'), $file, $version ) . $message, _wp_debug_error_type() );
 	}
 }
 /**
@@ -2905,9 +2905,9 @@
 	// Allow plugin to filter the output error trigger
 	if ( WP_DEBUG && apply_filters( 'deprecated_argument_trigger_error', true ) ) {
 		if ( ! is_null( $message ) )
-			trigger_error( sprintf( __('%1$s was called with an argument that is <strong>deprecated</strong> since version %2$s! %3$s'), $function, $version, $message ) );
+			trigger_error( sprintf( __('%1$s was called with an argument that is <strong>deprecated</strong> since version %2$s! %3$s'), $function, $version, $message ), _wp_debug_error_type() );
 		else
-			trigger_error( sprintf( __('%1$s was called with an argument that is <strong>deprecated</strong> since version %2$s with no alternative available.'), $function, $version ) );
+			trigger_error( sprintf( __('%1$s was called with an argument that is <strong>deprecated</strong> since version %2$s with no alternative available.'), $function, $version ), _wp_debug_error_type() );
 	}
 }
 
@@ -2941,11 +2941,32 @@
 	if ( WP_DEBUG && apply_filters( 'doing_it_wrong_trigger_error', true ) ) {
 		$version = is_null( $version ) ? '' : sprintf( __( '(This message was added in version %s.)' ), $version );
 		$message .= ' ' . __( 'Please see <a href="http://codex.wordpress.org/Debugging_in_WordPress">Debugging in WordPress</a> for more information.' );
-		trigger_error( sprintf( __( '%1$s was called <strong>incorrectly</strong>. %2$s %3$s' ), $function, $message, $version ) );
+		trigger_error( sprintf( __( '%1$s was called <strong>incorrectly</strong>. %2$s %3$s' ), $function, $message, $version ), _wp_debug_error_type() );
 	}
 }
 
 /**
+ * Returns the error type that should be used for deprecated and wrong behavior.
+ *
+ * Normally, E_USER_NOTICE is issued. E_USER_WARNING is issued for development builds (up to RC1).
+ *
+ * @subpackage Debug
+ * @since 3.6.0
+ * @access private
+ */
+function _wp_debug_error_type() {
+	static $error_type = null;
+	if ( isset( $error_type ) )
+		return $error_type;
+
+	include ABSPATH . WPINC . '/version.php';
+	$error_type = E_USER_NOTICE;
+	if ( strpos( $wp_version, '-' ) && ( strpos( $wp_version, '-alpha' ) || strpos( $wp_version, '-beta' ) || strpos( $wp_version, '-RC1' ) ) )
+		$error_type = E_USER_WARNING;
+	return $error_type;
+}
+
+/**
  * Is the server running earlier than 1.5.0 version of lighttpd?
  *
  * @since 2.5.0