General: Correctly detect trailing newline when prepending.

We need to check that the final line is actually an artifact of explode(), not just an empty input string.

See #37082.

Built from https://develop.svn.wordpress.org/trunk@39592


git-svn-id: http://core.svn.wordpress.org/trunk@39532 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/pomo/po.php

@@ -169,7 +169,7 @@ class PO extends Gettext_Translations {
 	public static function prepend_each_line($string, $with) {
 		$lines = explode("\n", $string);
 		$append = '';
-		if ('' === end($lines)) {
+		if ("\n" === substr($string, -1) && '' === end($lines)) {
 			// Last line might be empty because $string was terminated
 			// with a newline, remove it from the $lines array,
 			// we'll restore state by re-terminating the string at the end

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.8-alpha-39591';
+$wp_version = '4.8-alpha-39592';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.