Problem with 'upper' class when nocaseglob

[Lukáš Bařinka]

The version number of Bash:
   GNU bash, version 4.4.11(1)-release

The hardware and operating system:
   x86_64-pc-linux-gnu, Debian GNU/Linux 9

A description of the bug behaviour:
   When the nocaseglob option is set, the [:upper:] class in pattern
   does not match capital or small letters. On the other hand,
   [:lower:] works fine.

A short script or ‘recipe’ which exercises the bug and may be used
to reproduce it:
   $ touch a A
   $ echo [[:upper:]]
   A
   $ shopt -s nocaseglob
   $ echo [[:lower:]]
   a A
   $ echo [[:upper:]]
   [[:upper:]]