Changes in glib\gwin32.c at g_win32_get_package_installation_directory_of_module() (version 2.41.3 till current) cause it returns path of interpreter (python.exe) instead of cleaned up hmodule path.

If added printouts such:
...
gchar *
g_win32_get_package_installation_directory_of_module (gpointer hmodule)
{
  gchar *filename;
  gchar *retval;
  gchar *p;
  wchar_t wc_fn[MAX_PATH];

  /* NOTE: it relies that GetModuleFileNameW returns only canonical paths */
  if (!GetModuleFileNameW (hmodule, wc_fn, MAX_PATH))
    return NULL;

  filename = g_utf16_to_utf8 (wc_fn, -1, NULL, NULL, NULL);
  printf(filename);
  if ((p = strrchr (filename, G_DIR_SEPARATOR)) != NULL)
    *p = '\0';

  retval = g_strdup (filename);

  do
    {
      p = strrchr (retval, G_DIR_SEPARATOR);
      printf(retval);
      if (p == NULL)
        break;

      *p = '\0';

      if (g_ascii_strcasecmp (p + 1, "bin") == 0 ||
          g_ascii_strcasecmp (p + 1, "lib") == 0)
        break;
    }
  while (p != NULL);

  if (p == NULL)
    {
      g_free (retval);
      retval = filename;
    }
  else
    g_free (filename);

#ifdef G_WITH_CYGWIN
  /* In Cygwin we need to have POSIX paths */
  {
    gchar tmp[MAX_PATH];

    cygwin_conv_to_posix_path (retval, tmp);
    g_free (retval);
    retval = g_strdup (tmp);
  }
#endif
  printf (retval);
  return retval;
}
...

returns:
C:\Python34\Lib\site-packages\gnome\libgirepository-1.0-1.dll
C:\Python34\Lib\site-packages\gnome
C:\Python34\Lib\site-packages
C:\Python34\Lib
C:\Python34

It show that initial hmodule path is correct but inside the loop it keep cut till C:\python34

C:\Python34\Lib\site-packages\gnome in inside PATH environment, doesnt have "bin" subfulder but have "lib" subfolder and is the expected retval.

This bug reproduced in python mode. In windows this causes GI fail to find relative typelibs repo. So this bug is critical.