message: Don't skip white space by default in from_stream.
  * Put a space at the beginning of your
  format string to recover this behavior.
diff: @@ -5448,7 +5448,7 @@ from_stream(std::basic_istream<CharT, Traits>& is, const CharT* fmt,
  {
  using namespace std;
  using namespace std::chrono;
  - typename basic_istream<CharT, Traits>::sentry ok{is};
  + typename basic_istream<CharT, Traits>::sentry ok{is, true};
  if (ok)
  {
  auto& f = use_facet<time_get<CharT>>(is.getloc());
  