Better error message if ucnhash cannot be found (obscure attribute

errors aren't that helpful), or doesn't contain what's expected from
it.  Also tweaked the test script so it compiles even if ucnhash is
missing.

Lib/test/test_ucn.py

@@ -10,6 +10,10 @@ from test_support import verify, verbose
 print 'Testing General Unicode Character Name, and case insensitivity...',
 
 # General and case insensitivity test:
+try:
+    # put all \N escapes inside exec'd raw strings, to make sure this
+    # script runs even if the compiler chokes on \N escapes
+    exec r"""
 s = u"\N{LATIN CAPITAL LETTER T}" \
     u"\N{LATIN SMALL LETTER H}" \
     u"\N{LATIN SMALL LETTER E}" \
@@ -37,6 +41,9 @@ s = u"\N{LATIN CAPITAL LETTER T}" \
     u"\N{LATIN SMALL LETTER P}" \
     u"\N{FULL STOP}"
 verify(s == u"The rEd fOx ate the sheep.", s)
+"""
+except UnicodeError, v:
+    print v
 print "done."
 
 import ucnhash
@@ -63,10 +70,12 @@ print "Found", count, "characters in the unicode name database"
 
 # misc. symbol testing
 print "Testing misc. symbols for unicode character name expansion....",
+exec r"""
 verify(u"\N{PILCROW SIGN}" == u"\u00b6")
 verify(u"\N{REPLACEMENT CHARACTER}" == u"\uFFFD")
 verify(u"\N{HALFWIDTH KATAKANA SEMI-VOICED SOUND MARK}" == u"\uFF9F")
 verify(u"\N{FULLWIDTH LATIN SMALL LETTER A}" == u"\uFF41")
+"""
 print "done."
 
 

Objects/unicodeobject.c

@@ -1240,15 +1240,15 @@ PyObject *PyUnicode_DecodeUnicodeEscape(const char *s,
                 PyObject *mod = 0, *v = 0;
                 mod = PyImport_ImportModule("ucnhash");
                 if (mod == NULL)
-                    goto onError;
+                    goto ucnhashError;
                 v = PyObject_GetAttrString(mod,"Unicode_Names_CAPI");
                 Py_DECREF(mod);
                 if (v == NULL)
-                    goto onError;
+                    goto ucnhashError;
                 unicode_names = PyCObject_AsVoidPtr(v);
                 Py_DECREF(v);
                 if (unicode_names == NULL)
-                    goto onError;
+                    goto ucnhashError;
             }
                 
             if (*s == '{') {
@@ -1311,6 +1311,11 @@ store:
 		goto onError;
     return (PyObject *)v;
     
+ ucnhashError:
+    PyErr_SetString(PyExc_UnicodeError,
+                    "\\N escapes not supported (can't load ucnhash module)");
+    return NULL;
+
  onError:
     Py_XDECREF(v);
     return NULL;