system language leak via reply: Changed reply_header behaviour (upstream) requires setting new preference

[tagnaq]

We used to set

mailnews.reply_header_authorwrote = %s

to prevent the disclosure of the system language.

With Thunderbird 31 and later this pref is deprecated and does not work anymore.
​https://bugzilla.mozilla.org/show_bug.cgi?id=1009585

New pref/fix:

mailnews.reply_header_authorwrotesingle = #1:

[ioerror]

This issue should be addressed in the next release.

[sukhbir]

Fixed. Thanks tagnaq!