Tested 1.8.0-rc.0 on the test suites of horde and delta_crdt, and everything works as expected 
.
I did notice that asdf install elixir 1.8.0-rc.0 didn’t work (even though 1.8.0-rc.0 is what you see if you do asdf list-all elixir), I had to use asdf install elixir 1.8.0-rc.0-otp-21 per @Eiji’s instructions.
Looks like there are some problems on hex.pm side!
<?xml version="1.0" encoding="UTF-8"?>
<Error><Code>AccessDenied</Code><Message>Access Denied</Message><RequestId>E0764140496F3262</RequestId><HostId>Zu/0DZRnI0zYvyB5ZTwsMgZ0U+ZlHni5GjLgkO7PZjIUD104IyeCDmcS+huWB1jmA8bAW/7xycw=</HostId></Error>
Link generated by asdf install script:
https://repo.hex.pm/builds/elixir/v1.8.0-rc.0.zip
Did your automated tools also stopped uploading zip files to repo.hex.pm?
All my tests using mock library are failing on 1.8-rc.0. It looks like it uncovered some bug in meck. See Does not check :meck.new return code, crashes in runtime on Elixir 1.8-rc.0 · Issue #96 · jjh42/mock · GitHub Crash when mocking Elixir 1.8-rc.0 compiled module · Issue #201 · eproxus/meck · GitHub
Apart from that issue all appears to be OK.
