Plural-Forms retained when copying PO to same language

languages/loco-translate.pot

@@ -3,7 +3,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: Loco Translate 2.6.0\n"
 "Report-Msgid-Bugs-To: https://wordpress.org/support/plugin/loco-translate/\n"
-"POT-Creation-Date: 2022-03-07 12:16+0000\n"
+"POT-Creation-Date: 2022-03-08 12:27+0000\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: \n"
@@ -107,7 +107,7 @@ msgstr[0] ""
 msgstr[1] ""
 
 #. Where %s is either PO or POT
-#: src/gettext/Compiler.php:243 src/admin/file/HeadController.php:80
+#: src/gettext/Compiler.php:239 src/admin/file/HeadController.php:80
 #, php-format
 msgid "%s file saved"
 msgstr ""
@@ -1053,7 +1053,7 @@ msgstr ""
 msgid "It needs configuring before you can do any translations"
 msgstr ""
 
-#: src/gettext/Compiler.php:136 src/gettext/Compiler.php:198
+#: src/gettext/Compiler.php:136 src/gettext/Compiler.php:194
 #, php-format
 msgid "JSON compilation failed for %s"
 msgstr ""
@@ -1456,11 +1456,11 @@ msgstr ""
 msgid "PO file missing"
 msgstr ""
 
-#: src/gettext/Compiler.php:239
+#: src/gettext/Compiler.php:235
 msgid "PO file saved and MO file compiled"
 msgstr ""
 
-#: src/gettext/Compiler.php:236
+#: src/gettext/Compiler.php:232
 msgid "PO file saved and MO/JSON files compiled"
 msgstr ""
 

readme.txt

@@ -106,6 +106,7 @@ We don't collect your data or snoop on you. See the [plugin privacy notice](http
 * Bumped WordPress version to 5.9.1
 * Removed Yandex API integration
 * Added loco_compile_script_reference filter
+* Plural-Forms retained when copying PO to same language
 
 = 2.5.8 =
 * Compatible with PHP 8.1

src/gettext/Data.php

@@ -221,7 +221,7 @@ public function getSourceDigest(){
      * @return Loco_gettext_Data
      */
     public function localize( Loco_Locale $locale, array $custom = [] ){
-        $date = gmdate('Y-m-d H:i').'+0000'; // <- forcing UCT
+        $date = gmdate('Y-m-d H:i').'+0000';
         // headers that must always be set if absent
         $defaults =  [
             'Project-Id-Version' => '',
@@ -241,6 +241,18 @@ public function localize( Loco_Locale $locale, array $custom = [] ){
             'X-Generator' => 'Loco https://localise.biz/',
             'X-Loco-Version' => sprintf('%s; wp-%s', loco_plugin_version(), $GLOBALS['wp_version'] ),
         ];
+        // Allow some existing headers to remain if PO was previously localized to the same language
+        $headers = $this->getHeaders();
+        $previous = Loco_Locale::parse( $headers->trimmed('Language') );
+        if( $previous->lang === $locale->lang ){
+            $header = $headers->trimmed('Plural-Forms');
+            if( preg_match('/^\\s*nplurals\\s*=\\s*\\d+\\s*;\\s*plural\\s*=/', $header) ) {
+                $required['Plural-Forms'] = $header;
+            }
+            if( $previous->region === $locale->region && $previous->variant === $locale->variant ){
+                unset( $required['Language-Team'] );
+            }
+        }
         // set user's preferred Last-Translator credit if configured
         if( function_exists('get_current_user_id') && get_current_user_id() ){
             $prefs = Loco_data_Preferences::get();