MobileFrontend appears to use an $wgMFNoindexPages that defaults to true (according to the extension page) to simply block indexing of mobile as a way of handling indexing "issues".
I believe the correct way to handle this is not to noindex but instead to include a rel=alternative with a media="..." pointing to the mobile site. The way that google describes.
Change 193756 had a related patch set uploaded (by Florianschmidtwelzow):
Hygiene: Correctly show relationship between desktop and mobile page
Change 193756 merged by jenkins-bot:
Hygiene: Correctly show relationship between desktop and mobile page
Can someone check the behavior on wikisource.org (group1, the change was deployed yesterday). At least on the desktop site it seems to not work? And if you click the mobile link, the canonical link seems to be false formatted, too, or is it just on my site (maybe a caching issue)? :/
This is working.
If you want to enable it you'll need to flip the switch here:
http://git.wikimedia.org/blob/operations/mediawiki-config.git/a7a32ef59f19cdb5c4ef409724280c2f2b56d7d2/wmf-config/mobile.php#L9
I suggest raising a bug/making the config change for that if that is indeed the intended behaviour.
Change 212021 had a related patch set uploaded (by Florianschmidtwelzow):
Hygiene: Correctly add alternate and canocial links
Change 212022 had a related patch set uploaded (by Florianschmidtwelzow):
Enable alternate and canonical links for mobile/desktop pages
Change 212022 abandoned by Florianschmidtwelzow:
Enable alternate and canonical links for mobile/desktop pages
Reason:
can be done later, too, it's just a small change, and there is some work that need to be done before this change.