setlocale: empty string is interpreted as the default locale

Author: steve-s

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/LocaleModuleBuiltins.java

@@ -48,6 +48,8 @@
 import java.util.List;
 import java.util.Locale;
 
+import org.graalvm.collections.EconomicMap;
+
 import com.oracle.graal.python.builtins.Builtin;
 import com.oracle.graal.python.builtins.CoreFunctions;
 import com.oracle.graal.python.builtins.PythonBuiltins;
@@ -62,8 +64,6 @@
 import com.oracle.truffle.api.dsl.NodeFactory;
 import com.oracle.truffle.api.dsl.Specialization;
 
-import org.graalvm.collections.EconomicMap;
-
 @CoreFunctions(defineModule = "_locale")
 public class LocaleModuleBuiltins extends PythonBuiltins {
     static final int LC_ALL = 6;
@@ -81,6 +81,10 @@ public static Locale fromPosix(String posixLocaleId) {
         if (posixLocaleId == null) {
             return null;
         }
+        if (posixLocaleId.isEmpty()) {
+            // per Python docs: empty string -> default locale
+            return Locale.getDefault();
+        }
 
         String language;
         String country = "";