Microsoft is now testing a new build of Windows 10 Mobile Version 1511 internally. Recently, Microsoft pushed build 10586.338 to Windows Insiders in the Release Preview Ring. However, the company has started testing a new build: 10586.420. Just like most of the previous 10586.xxx updates, this build does not include any new features. Of course, the build should include a few bug fixes and improvements which are always appreciated.
For those wondering, it isn’t yet known when the build will get pushed out to the public or Insiders. As per usual, if the build passes all the internal testing, Microsoft will be pushing it out to Insiders first, and then to the Public.