Release Scala 2.12.18-M1

[SethTisue]

context is https://github.com/scala/scala/pull/10306 — we need to re-bootstrap in order to test on JDK 20

Stage

• [x] Make sure there are no stray staging repos on Sonatype
• [x] Trigger a custom build on travis
  • Select the correct branch
  • Custom config: before_script: export SCALA_VER_BASE=2.12.18 SCALA_VER_SUFFIX=-M1
  • https://app.travis-ci.com/github/scala/scala/builds/261190532
  • [x] Create the scala/scala tag locally: git tag -s -m "Scala 2.12.18-M1" v2.12.18-M1 5ce767fa2b295d0cb4ef56014ede18efbc90ea9c

Release! (point of hard no-return)

• [x] Push scala/scala tag: git push https://github.com/scala/scala.git v2.12.18-M1
• [x] Promote staging repos (using oss.sonatype.org web UI)

Check availability

• [x] Find the release on maven central: https://repo1.maven.org/maven2/org/scala-lang/scala-compiler/$SCALA_VER/

Afterwards

• [x] Create a scala/scala PR to:
  • [x] update starr.version in /versions.properties

[SethTisue]

"server redirected too many times" problems reminiscent of https://github.com/scala/scala-dev/issues/783 :-/

[SethTisue]

I verified that the same "server redirected too many times" thing happens if I try to build 2.13.11-M1

I think I need to regenerate the Travis-CI secrets, like last time (https://github.com/scala/scala-dev/issues/783#issuecomment-918759252)

[SethTisue]

I pushed scala/scala@5ce767fa2b295d0cb4ef56014ede18efbc90ea9c directly to 2.12.x, but it'll take a while to see whether it worked, since the integration build is in the queue before the triggered build (https://app.travis-ci.com/github/scala/scala/builds/261190532)

[SethTisue]

That worked.