Check for encoded Gnus group names when parsing active info

* lisp/gnus/gnus-start.el (gnus-active-to-gnus-format): NNTP serves
  may send encoded non-ascii group names.
1 job for scratch/gnus-decoded in 56 minutes and 3 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Test
passed #2234
test-all

00:56:03