"Composer update" keeps swapping packages from new-old-new-old versions around 8.3.0 upgrade

Hi all, I ran into a funny situation when updating to Drupal 8.3.0 from the 8.2.x series. When I used composer update, the packages kept swapping back and forth in a repeating cycle (downgrade-upgrade-downgrade-upgrade)

I was able to break out of this by deleting the whole vendor library and running 'composer update' from scratch. I also removed composer.lock . Now everything is fine.

Here is what the issue looked like when it was happening:

....$ composer update
> DrupalProject\composer\ScriptHandler::checkComposerVersion
Loading composer repositories with package information
Updating dependencies (including require-dev)
Package operations: 2 installs, 10 updates, 0 removals
  - Updating doctrine/collections (v1.3.0 => v1.4.0): Loading from cache
  - Updating symfony/expression-language (v2.8.19 => v3.1.10): Loading from cache
  - Updating symfony/dom-crawler (v3.2.7 => v3.1.10): Loading from cache
  - Installing psr/cache (1.0.1): Loading from cache
  - Installing symfony/cache (v3.1.10): Loading from cache
  - Updating psy/psysh (v0.8.3 => v0.8.0): Loading from cache
  - Updating symfony/filesystem (v2.8.19 => v3.1.10): Loading from cache
  - Updating symfony/config (v2.8.19 => v3.1.10): Loading from cache
  - Updating drupal/console-en (1.0.0-rc16 => 1.0.0-rc14): Loading from cache
  - Updating dflydev/dot-access-configuration (v1.0.1 => dev-master ae6e713):  Checking out ae6e7138b1
  - Updating drupal/console-core (1.0.0-rc16 => 1.0.0-rc14): Loading from cache
  - Updating drupal/console (1.0.0-rc16 => 1.0.0-rc14): Loading from cache
Writing lock file
Generating autoload files
> DrupalProject\composer\ScriptHandler::createRequiredFiles
....$ composer update
> DrupalProject\composer\ScriptHandler::checkComposerVersion
Loading composer repositories with package information
Updating dependencies (including require-dev)
Package operations: 1 install, 10 updates, 2 removals
  - Removing symfony/cache (v3.1.10)
  - Removing psr/cache (1.0.1)
  - Updating symfony/expression-language (v3.1.10 => v2.8.19): Loading from cache
  - Updating symfony/dom-crawler (v3.1.10 => v3.2.7): Loading from cache
  - Updating psy/psysh (v0.8.0 => v0.8.3): Loading from cache
  - Installing drupal/console-extend-plugin (0.4.0): Loading from cache
  - Updating symfony/filesystem (v3.1.10 => v2.8.19): Loading from cache
  - Updating symfony/config (v3.1.10 => v2.8.19): Loading from cache
  - Updating drupal/console-en (1.0.0-rc14 => 1.0.0-rc16): Loading from cache
  - Updating dflydev/dot-access-configuration (dev-master ae6e713 => v1.0.1):  Checking out 9b65c83159
  - Updating drupal/console-core (1.0.0-rc14 => 1.0.0-rc16): Loading from cache
  - Updating doctrine/collections (v1.4.0 => v1.3.0): Loading from cache
  - Updating drupal/console (1.0.0-rc14 => 1.0.0-rc16): Loading from cache
Writing lock file
Generating autoload files
> DrupalProject\composer\ScriptHandler::createRequiredFiles

And continues repeating like this.