Android 6.0 Marshmallow has rolled out to most of the Nexus family of devices, and now the race is on for OEM manufacturers to prepare Android M for their devices, complete testing, and roll out an OTA update.

And with the latest leaked picture showing a soak test, it looks like in 2015, as was the case last year, Motorola's Moto X is right on track to get an official OTA rollout of Google's latest Android OS before any other manufacturers' update release dates hit.

Motorola has a track record of getting Android updates out to its flagship devices before the likes of HTC, Samsung or LG. Last year, the Moto X 2014 was the first non-Nexus device to be upgraded to Android 5.0 Lollipop, with OTA rollout arriving as early as late November.

We're already into December, and as the latest evidence leaked to AndroidPolice by an anonymous reader shows, the Moto X Style is due for a wide update release sometime, and probably sooner than any other non-Nexus device in the U.S.

As Latin Post previously reported, Motorola's devices had already experienced (rumored) soak tests -- limited trials of new firmware shared only to Motorola users that participate in its support program -- as far back as October 2015.

The soak test for the Moto X 2015, however, was verified by a screenshot sent to AndroidPolice this week. And the Verizon Wireless and "Pure Edition" branding proves that the tests are occurring in the U.S., not Europe or any other test markets where the device name would state "Moto X Style."

The anonymous source said the soak test hit his Moto X Pure Edition on Tuesday of this week. The screenshot shows the update to be about 650MB, which matches the footprint of this year's more diminutive Android 6.0 Marshmallow update, as well as the size of Android M updates previously seen on Nexus devices this year.

And while soak tests aren't an indication that an OTA rollout is happening imminently, it certainly indicates more progress towards an Android update release date than has been seen for any other Android device in the U.S. No such evidence of late-stage testing has been leaked for Samsung's 2015 flagships -- or HTC and LG's devices, for that matter.

It has been somewhat confounding that Android 6.0 Marshmallow -- an update that is, by all indications, far less complex and smaller than the Android 5.0 Lollipop upgrade in 2014 -- has taken this long to hit any non-Nexus devices in Android world.

But perhaps Moto X Pure Edition users can hope for an OTA update notification sometime in December, whereas all other Android users are probably going to be stuck waiting until 2016 before they get their Marshmallow.