api: fix memory leak in function string_split

ChangeLog.adoc

@@ -28,6 +28,7 @@ Bug fixes::
   * core: fix check of tags in lines (command /filter and hook_print)
   * core: fix clear of completion item in case of partial completion (issue #1162)
   * core: send signal "key_pressed" for mouse code only if the string is UTF-8 valid (issue #1220)
+  * api: fix memory leak in function string_split
   * scripts: fix duplicated lines in output of script eval (python, perl, ruby, lua and guile)
 
 [[v2.2]]

src/core/wee-string.c

@@ -1752,8 +1752,13 @@ string_split_internal (const char *string, const char *separators, int keep_eol,
         return NULL;
 
     string2 = string_strip (string, 1, (keep_eol == 2) ? 0 : 1, separators);
-    if (!string2 || !string2[0])
+    if (!string2)
         return NULL;
+    if (!string2[0])
+    {
+        free (string2);
+        return NULL;
+    }
 
     /* calculate number of items */
     ptr = string2;