Fix a reference leak found by Georg, when compiling a class nested in another class.
Test is run with "regrtest.py -R:: test_compile"
Backport of r62015
diff --git a/Python/compile.c b/Python/compile.c
index f40c325..d40357c 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -2061,6 +2061,7 @@
if (!compiler_enter_scope(c, s->v.ClassDef.name, (void *)s,
s->lineno))
return 0;
+ Py_XDECREF(c->u->u_private);
c->u->u_private = s->v.ClassDef.name;
Py_INCREF(c->u->u_private);
str = PyString_InternFromString("__name__");