Auto complete seems to fail for strings beginning with `:`

[zxul767]

I'm using the library as a submodule, with a snapshot at commit c9310ae.

It works great for completing regular words, but I recently added some commands that start with : (e.g., :toggle-tracing), and I noticed that the auto completion doesn't seem to work for those words. For example, after configuring as follows:

static char* const TOGGLE_TRACING = ":toggle-tracing";
static char* const EXIT = "exit";

static const char* COMMANDS[] = {TOGGLE_TRACING, EXIT, NULL};

static void
word_completer(ic_completion_env_t* input_until_cursor, const char* word)
{
  ic_add_completions(input_until_cursor, word, COMMANDS);
}

static void
completer(ic_completion_env_t* input_until_cursor, const char* input)
{
  ic_complete_word(
      input_until_cursor, input, &word_completer,
      NULL /* from default word boundary; whitespace or separator */
  );
}

static void setup_line_reader()
{
  setlocale(LC_ALL, "C.UTF-8");

  ic_style_def("kbd", "gray underline");
  ic_style_def("ic-prompt", "ansi-maroon");
  ic_enable_hint(false);

  // enable completion with a default completion function
  ic_set_default_completer(&completer, NULL);
  ic_enable_auto_tab(true);
}

If I type : followed by TAB, I get:

>>> :
 1 exit
 2 :toggle-tracing

However, if I type: :t followed by TAB, I don't get any completions.

Is this expected behavior, a bug, or am I doing something wrong?

Thanks!