YAML: Unstable array formatting

[fisker]

Prettier 2.0.5
Playground link

--parser yaml

Input:

    needs:
      [
        check-format,
        check-lint,
        check-spelling,
        # coverage,
        # install-and-run-from-git,
      ]

    steps:

Output:

needs: [check-format, check-lint, check-spelling]

# coverage,
# install-and-run-from-git,
steps:

Prettier 2.0.5
Playground link

--parser yaml

Input:

    needs:
      # prettier-ignore
      [
        check-format,
        check-lint,
        check-spelling,
        # coverage,
        # install-and-run-from-git,
      ]

    steps:

Output:

needs:
  # prettier-ignore
  [
        check-format,
        check-lint,
        check-spelling,
        # coverage,
        # install-and-run-from-git,
      ]

# coverage,
# install-and-run-from-git,
steps:

Second Output:

needs:
  # prettier-ignore
  [
        check-format,
        check-lint,
        check-spelling,
        # coverage,
        # install-and-run-from-git,
      ]

# coverage,
# install-and-run-from-git,
# coverage,
# install-and-run-from-git,
steps:

---

original post by @cinderblock #6952 (comment)

Another manifestation of what I presume is the same bug. You can't even fix it with prettier-ignore.

Input

    needs:
      [
        check-format,
        check-lint,
        check-spelling,
        # coverage,
        # install-and-run-from-git,
      ]

    steps:

Output

    needs: [check-format, check-lint, check-spelling]

    # coverage,
    # install-and-run-from-git,
    steps:

I expected no change. There seem to be two things happening here:

1. Comments are being removed from the list. I don't think this is generally desirable. A common thing in JS for instance is to comment a single line from a list of things and that comment isn't taken out of the list.
2. Comments are not allowed to be "after" a section and are forced to be used as comments that seem to describe the next section. Empty lines around comments should be preserved, imho.

---

If I try to "fix" this with # prettier-ignore, it breaks even worse:

Input

    needs:
      # prettier-ignore
      [
        check-format,
        check-lint,
        check-spelling,
        # coverage,
        # install-and-run-from-git,
      ]
    steps:

Output

    needs:
      # prettier-ignore
      [
        check-format,
        check-lint,
        check-spelling,
        # coverage,
        # install-and-run-from-git,
      ]
    # coverage,
    # install-and-run-from-git,
    steps:

This is also "unstable" as every time I autofix, Prettier replicates the comments. After "formatting" 5 times:

Output

    needs:
      # prettier-ignore
      [
        check-format,
        check-lint,
        check-spelling,
        # coverage,
        # install-and-run-from-git,
      ]
    # coverage,
    # install-and-run-from-git,
    # coverage,
    # install-and-run-from-git,
    # coverage,
    # install-and-run-from-git,
    # coverage,
    # install-and-run-from-git,
    # coverage,
    # install-and-run-from-git,
    steps: