For those who bought a Nexus tablet or smartphone from the Google Play Store, the Android M (or Android 6.0 Marshmallow) update has already rolled out to their devices. However, that hasn't been the case for T-Mobile branded Nexus 6 users, who were promised an update in early October, and only now should be finally getting an OTA rollout of Android M soon.

T-Mobile had announced the imminent rollout of Android 6.0 Marshmallow to its Nexus devices -- like the Nexus 5, Nexus 6, and Nexus Player -- in the first days of October, as Latin Post previously reported.

But for Nexus 6 owners, a month and a half went by after the announcement and subsequent OTA rollout and nothing happened. No update notifications hit the wireless carriers' Nexus 6 devices throughout the Nexus rollout.

Now, T-Mobile has announced through its Twitter representative Des Smith @askdes (via TMoNews) that the update should finally start rolling out to the carriers' Nexus 6 devices soon.

Smith also recently explained the reason why the Android Marshmallow update rollout for particularly the Nexus 6 was delayed so much, while other Nexus devices were up and running with the latest mobile OS from Google by mid-October.

According to TMoNews, while going through routine testing of Android M builds, T-Mobile spotted a huge bug for the Nexus 6 in particular. Because of that, the carrier had to get a new build of Android Marshmallow, tailor it to the Nexus 6, and then go through the testing process again.

Meanwhile, Nexus 6 users for the carrier weren't able to update their devices with stock Android 6.0 Marshmallow from Google -- the way other Nexus 6 users got their updates -- because T-Mobile had to have a special build of Android M that supported WiFi calling, as well as supporting one of T-Mobile's unique LTE bands.

But now that back-to-the-drawing-board update is nearing completion, and should be pushed out to the carriers' Nexus 6 devices very soon.