BUG: "git checkout" displays Q-escaped commit titles

When commit message's first line (i.e. the title) contains non-Ascii characters "git checkout <commit>" displays this title in Q-escaped form which looks something like this: =?utf-8?q?=C3=84=C3=A4kk=C3=B6si=C3=A4?=

Steps to reproduce:

$ mkdir repo
$ cd repo
$ git init
$ echo stuff >file
$ git add file
$ git commit -m "Ääkkösiä"
$ git checkout $(git rev-list -1 HEAD)
Note: moving to "dc968d26f2fb74a6991c03798ee1d7aab458548a" which isn't a local branch
If you want to create a new branch from this checkout, you may do so
(now or later) by using -b with the checkout command again. Example:
  git checkout -b <new_branch_name>
HEAD is now at dc968d2... =?utf-8?q?=C3=84=C3=A4kk=C3=B6si=C3=A4?=