Fix Mac build, patch #1091 by Humberto Diogenes.
diff --git a/Lib/plat-mac/macresource.py b/Lib/plat-mac/macresource.py
index 14581a3..4592ff5 100644
--- a/Lib/plat-mac/macresource.py
+++ b/Lib/plat-mac/macresource.py
@@ -76,15 +76,15 @@
     AppleSingle file"""
     try:
         refno = Res.FSpOpenResFile(pathname, 1)
-    except Res.Error as arg:
-        if arg[0] in (-37, -39):
+    except Res.Error as error:
+        if error.args[0] in (-37, -39):
             # No resource fork. We may be on OSX, and this may be either
             # a data-fork based resource file or a AppleSingle file
             # from the CVS repository.
             try:
                 refno = Res.FSOpenResourceFile(pathname, '', 1)
-            except Res.Error as arg:
-                if arg[0] != -199:
+            except Res.Error as error:
+                if error.args[0] != -199:
                     # -199 is "bad resource map"
                     raise
             else:
@@ -103,15 +103,15 @@
     try:
         refno = Res.FSpOpenResFile(pathname, 1)
         Res.CloseResFile(refno)
-    except Res.Error as arg:
-        if arg[0] in (-37, -39):
+    except Res.Error as error:
+        if error.args[0] in (-37, -39):
             # No resource fork. We may be on OSX, and this may be either
             # a data-fork based resource file or a AppleSingle file
             # from the CVS repository.
             try:
                 refno = Res.FSOpenResourceFile(pathname, '', 1)
-            except Res.Error as arg:
-                if arg[0] != -199:
+            except Res.Error as error:
+                if error.args[0] != -199:
                     # -199 is "bad resource map"
                     raise
             else: