Add some failing tests for GH #1864, but disable them.

tests/run/py34_signature.pyx

@@ -89,3 +89,28 @@ def n(a, *, b, c = 88):
     >>> def py_n(a, *, b, c = 88): pass
     >>> signatures_match(n, py_n)
     """
+
+
+cpdef cp1(a, b):
+    """
+    >>> def py_cp1(a, b): pass
+    >>> signatures_match(cp1, py_cp1)
+    """
+
+
+# Currently broken, see GH #1864
+cpdef cp2(a, b=True):
+    """
+    >>> def py_cp2(a, b=True): pass
+
+    #>>> signatures_match(cp2, py_cp2)
+    """
+
+
+# Currently broken, see GH #1864
+cpdef cp3(a=1, b=True):
+    """
+    >>> def py_cp3(a=1, b=True): pass
+
+    #>>> signatures_match(cp3, py_cp3)
+    """