Gabe Aul, Microsoft's group head for the Windows Insider Program, has revealed through Twitter that they are currently testing build 10136 in the OSG Slow Ring as the next Windows 10 Mobile candidate for release to Insiders.
The last potential build we heard about was 10134 just last week. According to Gabe Aul, the build felt "really good", but had an update bug, relating to upgrading, holding it back. We got to see some of the changes that are coming in a series of leaked screenshots showing graphical changes and tweaks to Project Spartan. Build 10134 even got some video treatment showing changes to settings and new pivoting gestures in the phone and alarm apps.
The last mobile build that was released to Insiders was build 10080 on May 14th, almost one month ago. This particular build had numerous new bugs which didn't allow it to be released to the slow ring, leaving slow ring insiders on build 9941.
With 10136 moving through the internal slow rings at Microsoft, it seems at though the update bug has been mostly worked out. Though we probably won't see a new build before the weekend, given that Aul stated they need two or three days more for testing, chances are looking good for a new Windows 10 Mobile build next week.