Raise ImportError if pyexpat's version is incompatible

diff --cc Modules/_elementtree.c
index a7201a5fcf0dcc195b94180da85b4cae35b459a1,c36af5d12616f8182992363d25046c4edfe68ec9..6f17d800ba801ba75fb028e4a4b8189962299436
--- 1/Modules/_elementtree.c
--- 2/Modules/_elementtree.c
+++ b/Modules/_elementtree.c
@@@ -3511,14 -3115,17 +3511,16 @@@ PyInit__elementtree(void
              expat_capi->MAJOR_VERSION != XML_MAJOR_VERSION ||
              expat_capi->MINOR_VERSION != XML_MINOR_VERSION ||
              expat_capi->MICRO_VERSION != XML_MICRO_VERSION) {
-             expat_capi = NULL;
+             PyErr_SetString(PyExc_ImportError,
+                             "pyexpat version is incompatible");
+             return NULL;
          }
-     }
-     if (!expat_capi)
+     } else {
          return NULL;
 -#endif
+     }
  
      elementtree_parseerror_obj = PyErr_NewException(
 -        "cElementTree.ParseError", PyExc_SyntaxError, NULL
 +        "xml.etree.ElementTree.ParseError", PyExc_SyntaxError, NULL
          );
      Py_INCREF(elementtree_parseerror_obj);
      PyModule_AddObject(m, "ParseError", elementtree_parseerror_obj);