In TFS, in the old XAML build definitions, when queueing build for "Latest sources with shelveset" (in the web interface at least) there is nice checkbox that allows you to "Check-in changes after successful build".
Now we've moved to the new vNext builds, and when queueing build (with shelveset), the nice checkbox isn't there.
Is there way to make auto checkin after successful manually-enqueued build? (I need it specifically in gated-build-definition, but want to do it through the web interface, and not with Visual Studio Check -In process).
There isn't the web gated check in policy for shelvesets in vNext build. We can only enable gated check-in build process in build definition and trigger it with Visual Studio Check-In process.
But you can try to add a Batch Script task as the end task, then run a tf checkin command to check in the shelveset, eg : tf checkin /shelveset:shelvesetname;shelvesetowner
Please see Checkin command on MSDN for more details.