This is not possible. Right now, it's on the list of a GSoC student of things to
address[1].
[1]
https://www.mediawiki.org/wiki/User:Kunalgrover05/GSoc_Proposal
--
Siebrand Mazeland
Kitano ICT
M: +31 6 50 69 1239
Skype: siebrand
Op 21 mei 2014 om 10:50 heeft KC Lau
<kc.kclau(a)gmail.com> het volgende geschreven:
My question is: is there a way to specify the source language for a translatable page
when it differs from the site language?