Fix displaying of the "An updated version of WordPress is available." notice when running the latest nightly build. Note that it is still displayed when running a local build or from `/src`.

Props afragen, audrasjb, SergeyBiryukov.
Fixes #45202.
Built from https://develop.svn.wordpress.org/trunk@45532


git-svn-id: http://core.svn.wordpress.org/trunk@45343 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/update-core.php

@@ -204,7 +204,9 @@ function core_upgrade_preamble() {
 			}
 		}
 		echo '</h2>';
-	} else {
+	}
+
+	if ( isset( $updates[0]->version ) && version_compare( $updates[0]->version, $wp_version, '>' ) ) {
 		echo '<div class="notice notice-warning"><p>';
 		_e( '<strong>Important:</strong> Before updating, please <a href="https://codex.wordpress.org/WordPress_Backups">back up your database and files</a>. For help with updates, visit the <a href="https://codex.wordpress.org/Updating_WordPress">Updating WordPress</a> Codex page.' );
 		echo '</p></div>';

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.3-alpha-45531';
+$wp_version = '5.3-alpha-45532';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.