fix exception usage

Lib/dummy_thread.py

@@ -79,8 +79,7 @@ def allocate_lock():
 def stack_size(size=None):
     """Dummy implementation of thread.stack_size()."""
     if size is not None:
-        msg = "setting thread stack size not supported on this platform"
-        warnings.warn(msg, RuntimeWarning)
+        raise error("setting thread stack size not supported")
     return 0
 
 class LockType(object):

Lib/test/test_thread.py

@@ -133,7 +133,7 @@ if os_name in ("nt", "os2", "posix"):
         thread.stack_size(4096)
     except ValueError:
         print 'caught expected ValueError setting stack_size(4096)'
-    except thread.ThreadError:
+    except thread.error:
         tss_supported = 0
         print 'platform does not support changing thread stack size'