tl;dr - We're on it but Beta 1 is special and the buildbots need more cowbell^H^H more green.
Today Victor's been very active helping getting the stable buildbots green. Two main issues that were blocking Beta 1 were: a coredump in new functionality for subinterpreters (BPO-33608) and asyncio tests being flaky by altering the environment (BPO-37137).
The former was solved by reverting the offending change. Victor did merge a few changes to help with the latter but it's sadly still red on the stable buildbots.
While it's "just" an altered environment, I'd feel really bad about releasing the first beta with three stable buildbots in the red. Thankfully, Andrew Svetlov is looking at the problem as you're reading this.
Another thing about Beta 1 is that it's the moment where the branch is cut, which also triggers quite a few required configuration changes in CI, Github, Buildbot, Roundup, and so on. Ned has been helping me understand the full scope of this today.
**Please avoid pushing last minute changes while we are trying to get the stable buildbots all green for release. Thanks for your understanding!**