Index: src/wp-admin/includes/class-wp-community-events.php
===================================================================
--- src/wp-admin/includes/class-wp-community-events.php	(revision 42252)
+++ src/wp-admin/includes/class-wp-community-events.php	(working copy)
@@ -114,7 +114,7 @@
 			$response_error = new WP_Error(
 				'api-error',
 				/* translators: %d: numeric HTTP status code, e.g. 400, 403, 500, 504, etc. */
-				sprintf( __( 'Invalid API response code (%d)' ), $response_code )
+				sprintf( __( 'Invalid API response code (%d).' ), $response_code )
 			);
 		} elseif ( ! isset( $response_body['location'], $response_body['events'] ) ) {
 			$response_error = new WP_Error(
Index: src/wp-admin/includes/media.php
===================================================================
--- src/wp-admin/includes/media.php	(revision 42252)
+++ src/wp-admin/includes/media.php	(working copy)
@@ -872,7 +872,7 @@
 		// Set variables for storage, fix file filename for query strings.
 		preg_match( '/[^\?]+\.(jpe?g|jpe|gif|png)\b/i', $file, $matches );
 		if ( ! $matches ) {
-			return new WP_Error( 'image_sideload_failed', __( 'Invalid image URL' ) );
+			return new WP_Error( 'image_sideload_failed', __( 'Invalid image URL.' ) );
 		}
 
 		$file_array = array();
Index: src/wp-includes/class-wp-metadata-lazyloader.php
===================================================================
--- src/wp-includes/class-wp-metadata-lazyloader.php	(revision 42252)
+++ src/wp-includes/class-wp-metadata-lazyloader.php	(working copy)
@@ -74,7 +74,7 @@
 	 */
 	public function queue_objects( $object_type, $object_ids ) {
 		if ( ! isset( $this->settings[ $object_type ] ) ) {
-			return new WP_Error( 'invalid_object_type', __( 'Invalid object type' ) );
+			return new WP_Error( 'invalid_object_type', __( 'Invalid object type.' ) );
 		}
 
 		$type_settings = $this->settings[ $object_type ];
@@ -114,7 +114,7 @@
 	 */
 	public function reset_queue( $object_type ) {
 		if ( ! isset( $this->settings[ $object_type ] ) ) {
-			return new WP_Error( 'invalid_object_type', __( 'Invalid object type' ) );
+			return new WP_Error( 'invalid_object_type', __( 'Invalid object type.' ) );
 		}
 
 		$type_settings = $this->settings[ $object_type ];
Index: src/wp-includes/widgets/class-wp-widget-rss.php
===================================================================
--- src/wp-includes/widgets/class-wp-widget-rss.php	(revision 42252)
+++ src/wp-includes/widgets/class-wp-widget-rss.php	(working copy)
@@ -69,7 +69,7 @@
 		}
 
 		if ( empty( $title ) ) {
-			$title = ! empty( $desc ) ? $desc : __( 'Unknown Feed' );
+			$title = ! empty( $desc ) ? $desc : __( 'Unknown Feed.' );
 		}
 
 		/** This filter is documented in wp-includes/widgets/class-wp-widget-pages.php */