I commit something to my local Mercurial repository and write the log message containing some umlauts using nano. I then push the changes to Phabricator. The resulting email contains `?` in subject and body, even though it has following headers set:
```
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Content-Type: text/plain; charset="utf-8"
```
Within Phabricator, the commit message also shows `?` instead of the umlauts. The generated site has `<meta charset="UTF-8">`.
I have set `LANG=en_GB.UTF-8` on my local system. The server Phabricator runs on supports the same locale. PHP has `default_charset = "UTF-8"` set.
The issue appears with HHVM 3.5.0 as well as PHP-FPM 5.5.21. It also showed (on the web and in emails) with old commits that were created when we were still using mod_php. I am running Apache 2.4.10-9 and MariaDB 10.0.15-3 on Debian 8 Jessie.