added disabled test case for type inference in generators

tests/bugs.txt

@@ -18,6 +18,7 @@ genexpr_iterable_lookup_T600
 for_from_pyvar_loop_T601
 decorators_T593
 temp_sideeffects_T654
+generator_type_inference
 
 # CPython regression tests that don't current work:
 pyregr.test_threadsignals

tests/run/generator_type_inference.pyx

+# mode: run
+# tag: typeinference, generators
+
+cimport cython
+
+def test_type_inference():
+    """
+    >>> [ item for item in test_type_inference() ]
+    [(2.0, 'double'), (2.0, 'double'), (2.0, 'double')]
+    """
+    x = 1.0
+    for i in range(3):
+        yield x * 2.0, cython.typeof(x)