Correctly figure out exc_info in ConsoleRenderer.

[aclemons]

Summary

If the exc_info key was filled with a raw exception, and not a tuple,
the ConsoleRenderer code would call sys.exc_info and overwrite it.
This is different to how the other processors handle the exc_info key.

Additionally, if that call to sys.exc_info returned None, an explosion
would happen. This is the case if we placed an exception in exc_info,
but did not actually log until outside of the except block.

Closes #482

Pull Request Check List

• Added tests for changed code.
  • The CI fails with less than 100% coverage.
• New APIs are added to typing_examples.py.
• Updated documentation for changed code.
  • New functions/classes have to be added to docs/api.rst by hand.
  • Changed/added classes/methods/functions have appropriate versionadded, versionchanged, or deprecated directives.
    Find the appropriate next version in our __init__.py file.
• Documentation in .rst and .md files is written using semantic newlines.
• Changes (and possible deprecations) are documented in the changelog.
• Consider granting push permissions to the PR branch, so maintainers can fix minor issues themselves without pestering you.

[hynek]

Thanks! Would you mind adding a regression test and a changelog entry please?

[aclemons]

@hynek Sorry for the delay. I've added some basic tests and an entry to the CHANGELOG.md

[hynek]

Thanks!