Also raise RuntimeError in libc.regex_first_group_match().

native/libc.c

@@ -302,8 +302,9 @@ func_regex_first_group_match(PyObject *self, PyObject *args) {
  // patterns like ${foo/x*/y}.

  if (regcomp(&pat, pattern, REG_EXTENDED) != 0) {
    fprintf(stderr, "Invalid regex at runtime\n");
    return PyLong_FromLong(-1);
    PyErr_SetString(PyExc_RuntimeError,
                    "Invalid regex syntax (func_regex_first_group_match)");
    return NULL;
  }

  debug("first_group_match pat %s str %s pos %d", pattern, str, pos);
@@ -338,7 +339,8 @@ static PyMethodDef methods[] = {
    "Raises RuntimeError if the regex is invalid."},
  {"regex_first_group_match", func_regex_first_group_match, METH_VARARGS,
   "If the regex matches the string, return the start and end position of the "
   "first group.  None for no match; -1 for invalid regex."},
   "first group.  Returns None if there is no match.  Raises RuntimeError if "
   "the regex is invalid."},
  {NULL, NULL},
};

native/libc_test.py

@@ -74,7 +74,7 @@ def testRegex(self):
      actual = libc.regex_match(pat, s)
      self.assertEqual(expected, actual)

    # Error.
    # Syntax Error
    self.assertRaises(
        RuntimeError, libc.regex_match, r'*', 'abcd')

@@ -94,6 +94,10 @@ def testRegexFirstGroupMatch(self):
        (8, 10),
        libc.regex_first_group_match('(X.)', s, 6))

    # Syntax Error
    self.assertRaises(
        RuntimeError, libc.regex_first_group_match, r'*', 'abcd', 0)

  def testRealpathFailOnNonexistentDirectory(self):
    # This behaviour is actually inconsistent with GNU readlink,
    # but matches behaviour of busybox readlink