[SPARK-3397] Bump pom.xml version number of master branch to 1.2.0-SNAPSHOT

[witgo]

No description provided.

[srowen]

@witgo The release process does this, I believe. I don't think you need to open a PR for this especially before 1.1.0 is released

[witgo]

@srowen I agree with you. But SparkContext.SPARK_VERSION has been modified to 1.2.0-SNAPSHOT

[tgravescs]

When we resolve and target jira for master its against 1.2, so why isn't the pom version updated? If its a release process detail, can we change it. I find it confusing that when I build against master its older then when I build against branch-1.1

[JoshRosen]

Actually, I think this is the right fix. Commits that are targeted for 1.1.0 go into branch-1.1, while development for 1.2.0 is continuing on master, so we probably should have updated the pom.xml versions when we created branch-1.1 itself, not when we released 1.1.0, so that the first commit/revision that's in 1.2.0 and not in 1.1.0 has the right version.

[pwendell]

Yeah I think it's reasonable to bump the versions in master now rather than wait for the release.

[tgravescs]

@pwendell do you just want to run the set version and commit it or do you want to do it through this jira?

[JoshRosen]

Checked with Patrick and this looks good, so I'm going to merge it. Thanks!

[JoshRosen]

It looks like this somehow broke the MiMa binary compatibility tests. I noticed that I merged this without first checking whether Jenkins had run; sorry about that! I'm going to dig in and see if I can figure out why this is causing failures...

[JoshRosen]

Aha! There was a "1.1" string in MimaExcludes:

 def excludes(version: String) =
      version match {
        case v if v.startsWith("1.1") =>
          Seq(
            MimaBuild.excludeSparkPackage("deploy"),
            MimaBuild.excludeSparkPackage("graphx")
          ) ++
          ...

I guess this logic serves to exclude certain incompatibilities introduced in Spark 1.1.

What's the right fix here (beyond just rolling back the version numbers, which I'll probably do in the interim)?

At the time of release, 1.1.0 should be binary-compatible with 1.0.0. Therefore, when testing 1.2.0-SNAPSHOT, is it safe to just update the previousSparkVersion to 1.1.0 and start with an empty set of excludes if v.startsWith(1.2)? This might have to wait until 1.1.0 is published on Maven.

/cc @pwendell