Index: includes/locale.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/locale.inc,v
retrieving revision 1.254
diff -u -p -r1.254 locale.inc
--- includes/locale.inc	1 May 2010 08:12:22 -0000	1.254
+++ includes/locale.inc	2 May 2010 06:20:03 -0000
@@ -685,30 +685,35 @@ function _locale_import_one_string($op, 
           // Since we only need to parse the header if we ought to update the
           // plural formula, only run this if we don't need to keep existing
           // data untouched or if we don't have an existing plural formula.
-          $header = _locale_import_parse_header($value['msgstr']);
-
-          // Get the plural formula and update in database.
-          if (isset($header["Plural-Forms"]) && $p = _locale_import_parse_plural_forms($header["Plural-Forms"], $file->uri)) {
-            list($nplurals, $plural) = $p;
-            db_update('languages')
-              ->fields(array(
-                'plurals' => $nplurals,
-                'formula' => $plural,
-              ))
-              ->condition('language', $lang)
-              ->execute();
+          if ($header_done) {
+            watchdog('locale', 'An empty message ID string was found during .po import.  The string was dropped.', array(), WATCHDOG_WARNING);
           }
           else {
-            db_update('languages')
-              ->fields(array(
-                'plurals' => 0,
-                'formula' => '',
-              ))
-              ->condition('language', $lang)
-              ->execute();
+            $header = _locale_import_parse_header($value['msgstr']);
+
+            // Get the plural formula and update in database.
+            if (isset($header["Plural-Forms"]) && $p = _locale_import_parse_plural_forms($header["Plural-Forms"], $file->uri)) {
+              list($nplurals, $plural) = $p;
+              db_update('languages')
+                ->fields(array(
+                  'plurals' => $nplurals,
+                  'formula' => $plural,
+                ))
+                ->condition('language', $lang)
+                ->execute();
+            }
+            else {
+              db_update('languages')
+                ->fields(array(
+                  'plurals' => 0,
+                  'formula' => '',
+                ))
+                ->condition('language', $lang)
+                ->execute();
+            }
+            $header_done = TRUE;
           }
         }
-        $header_done = TRUE;
       }
 
       else {
@@ -1234,9 +1239,9 @@ function _locale_parse_js_file($filepath
  */
 
 /**
- * Generates a structured array of all strings with translations in
- * $language, if given. This array can be used to generate an export
- * of the string in the database.
+ * Generates a structured array of all non-empty source strings with
+ * translations in $language, if given. This array can be used to generate an
+ * export of the string in the database.
  *
  * @param $language
  *   Language object to generate the output for, or NULL if generating
@@ -1246,10 +1251,10 @@ function _locale_parse_js_file($filepath
  */
 function _locale_export_get_strings($language = NULL, $group = 'default') {
   if (isset($language)) {
-    $result = db_query("SELECT s.lid, s.source, s.context, s.location, t.translation, t.plid, t.plural FROM {locales_source} s LEFT JOIN {locales_target} t ON s.lid = t.lid AND t.language = :language WHERE s.textgroup = :textgroup ORDER BY t.plid, t.plural", array(':language' => $language->language, ':textgroup' => $group));
+    $result = db_query("SELECT s.lid, s.source, s.context, s.location, t.translation, t.plid, t.plural FROM {locales_source} s LEFT JOIN {locales_target} t ON s.lid = t.lid AND t.language = :language WHERE s.textgroup = :textgroup AND s.source != '' ORDER BY t.plid, t.plural", array(':language' => $language->language, ':textgroup' => $group));
   }
   else {
-    $result = db_query("SELECT s.lid, s.source, s.context, s.location, t.plid, t.plural FROM {locales_source} s LEFT JOIN {locales_target} t ON s.lid = t.lid WHERE s.textgroup = :textgroup ORDER BY t.plid, t.plural", array(':textgroup' => $group));
+    $result = db_query("SELECT s.lid, s.source, s.context, s.location, t.plid, t.plural FROM {locales_source} s LEFT JOIN {locales_target} t ON s.lid = t.lid WHERE s.textgroup = :textgroup AND s.source != '' ORDER BY t.plid, t.plural", array(':textgroup' => $group));
   }
   $strings = array();
   foreach ($result as $child) {
Index: modules/locale/locale.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/locale/locale.module,v
retrieving revision 1.292
diff -u -p -r1.292 locale.module
--- modules/locale/locale.module	29 Apr 2010 05:15:43 -0000	1.292
+++ modules/locale/locale.module	2 May 2010 06:20:12 -0000
@@ -634,6 +634,12 @@ function locale($string = NULL, $context
 
   $langcode = isset($langcode) ? $langcode : $language->language;
 
+  if ($string === '') {
+    // Avoid checking for empty strings and also creating empty strings in the
+    // translation database.
+    return '';
+  }
+
   // Store database cached translations in a static variable. Only build the
   // cache after $language has been set to avoid an unnecessary cache rebuild.
   if (!isset($locale_t[$langcode]) && isset($language)) {