rev-parse -q --verify with not existent upstream branch

Documentation to git-rev-parse claims that

-q, --quiet
   Only meaningful in --verify mode. Do not output an error
   message if the first argument is not a valid object name; instead exit
   with non-zero status silently.


However when I try to check if the current branch has a configured
upstream one with:

git rev-parse -q --verify  '@{u}'

I still receives the error message:

error: No upstream configured for branch 'threading'

Additinally withour -q --verify options the error message is printed
twice:

error: No upstream configured for branch 'threading'
@{u}
error: No upstream configured for branch 'threading'
fatal: ambiguous argument '@{u}': unknown revision or path not in the
working tree.
Use '--' to separate paths from revision

-- 
  Kacper