Revert "Switch to StdioInputMethod when TERM is 'dumb' (#907)"

[tompng]

Reverts #907 to avoid ruby/ruby CI failure and Debug compatibility test failure

[st0012]

@dgutov sorry that we need to revert your PR for now as it'd break Ruby CI and block other Ruby committer's work.

This is because as part of its CI suites, debug (bundled gem) will be tested against the latest ruby/ruby, which includes IRB commits synced there. And currently debug's tests rely on the TERM=dumb behaviour before you PR. But unlike IRB, debug is only synced to ruby/ruby when a release happens.

This means that to prevent Ruby CI from failing, we will need to:

1. patch debug to adjust for your change
2. And then cut a release with it

But unfortunately we don't have control over the debug project, so we need to coordinate with its maintainer.

[dgutov]

That's too bad, but ok.

Could you please Cc me when you file the corresponding issue or PR to the debug repo?

[tompng]

@dgutov Thank you for fixing #907, and sorry for making confusion.

With the workaround #943, now we don't need to revert.
I've opened a pull request to debug ruby/debug#1100 that fixes the test to pass without the workaround.

[dgutov]

Thanks.

The new workaround is not ideal (an extra newline is unexpected), but it's still better than Irb being entirely non-functional. Looking forward to having it reverted after all test suites are updated.