Partial backport of r78826: leave import site error handler unchanged (print
the error and continue).

Merged revisions 78826-78827 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk

........
  r78826 | victor.stinner | 2010-03-10 23:30:19 +0100 (mer., 10 mars 2010) | 5 lines

  Issue #3137: Don't ignore errors at startup, especially a keyboard interrupt
  (SIGINT). If an error occurs while importing the site module, the error is
  printed and Python exits. Initialize the GIL before importing the site
  module.
........
  r78827 | victor.stinner | 2010-03-10 23:45:04 +0100 (mer., 10 mars 2010) | 4 lines

  ooops, fix error message in execusercustomize()

  Copy/paste failure :-)
........
diff --git a/Parser/tokenizer.c b/Parser/tokenizer.c
index 79f1fa8..b84a154 100644
--- a/Parser/tokenizer.c
+++ b/Parser/tokenizer.c
@@ -764,8 +764,12 @@
 	return -1;
 
 error_clear:
-	/* Fallback to iso-8859-1: for backward compatibility */
 	Py_DECREF(enc);
+	if (!PyErr_ExceptionMatches(PyExc_UnicodeDecodeError)) {
+		tok->done = E_ERROR;
+		return -1;
+	}
+	/* Fallback to iso-8859-1: for backward compatibility */
 	PyErr_Clear();
 	return 0;
 }