Index: wp-includes/class-http.php
===================================================================
--- wp-includes/class-http.php	(revision 20674)
+++ wp-includes/class-http.php	(working copy)
@@ -535,6 +535,24 @@
 			return !in_array( $check['host'], $accessible_hosts ); //Inverse logic, If its in the array, then we can't access it.
 
 	}
+
+	static function make_absolute_url( $relative_path, $url ) {
+		if ( empty( $url ) )
+			return $relative_path;
+
+		// Check for a scheme
+		if ( false !== strpos( $relative_path, '://' ) )
+			return $relative_path;
+
+		if ( ! $url_parts = @parse_url( $url ) )
+			return $relative_path;
+
+		$absolute_path = $url_parts['scheme'] . '://' . $url_parts['host'];
+		if ( isset( $url_parts['port'] ) )
+			$absolute_path .= ':' . $url_parts['port'];
+
+		return $absolute_path . '/' . ltrim( $relative_path, '/' );
+	}
 }
 
 /**
@@ -730,7 +748,7 @@
 		// If location is found, then assume redirect and redirect to location.
 		if ( isset($arrHeaders['headers']['location']) && 0 !== $r['_redirection'] ) {
 			if ( $r['redirection']-- > 0 ) {
-				return $this->request($arrHeaders['headers']['location'], $r);
+				return $this->request( WP_HTTP::make_absolute_url( $arrHeaders['headers']['location'], $url ), $r);
 			} else {
 				return new WP_Error('http_request_failed', __('Too many redirects.'));
 			}
@@ -1131,7 +1149,7 @@
 		// See #11305 - When running under safe mode, redirection is disabled above. Handle it manually.
 		if ( ! empty( $theHeaders['headers']['location'] ) && 0 !== $r['_redirection'] ) { // _redirection: The requested number of redirections
 			if ( $r['redirection']-- > 0 ) {
-				return $this->request( $theHeaders['headers']['location'], $r );
+				return $this->request( WP_HTTP::make_absolute_url( $theHeaders['headers']['location'], $url ), $r );
 			} else {
 				return new WP_Error( 'http_request_failed', __( 'Too many redirects.' ) );
 			}