Problem/Motivation
On #2886609-50: Migrate D6 i18n translations of taxonomy vocabulary/terms, I tested migrating a D6 site into D8, as follows:
a) Downloaded latest drupal 8.6.x dev tgz file from drupal.org (easier than git for me for Drupal core at the moment).
b) Installed Drupal from the UI, using the Minimal install profile, and configured site without Update module.
c) Turned on Seven/Bartik themes, and a bunch of core modules: Migrate, Migrate Drupal *UI, Migrate Drupal UI; all 4 multilingual modules; Toolbar; plus some my migrated d6 site would need: Taxonomy, Views, a bunch of field modules, custom blocks and custom menu items. Note at this point there are no content types or vocabularies in my D8 database, and no node or term data.
d) Went to /upgrade, clicked Continue, and entered the site database/files information from a D6 site that I wanted to migrate. This site has 2 languages, and some translated nodes and taxonomy terms in it.
e) Got this warning on the next page:
Problems with this:
- The warning says "WARNING: Content may be overwritten on your new site", but I have no content to be overwritten.
- In order to continue, I have to click a button saying "I acknowledge I may lose data. Continue anyway". This sounds like a legal disclaimer, and again, I have no data in my site to lose.
- (minor) The more information link text says "Upgrade handbook" but we don't really use the word "handbook" to refer to community documentation pages any more. Or at least, we shouldn't. The page title is "Known issues when upgrading from Drupal 6 or 7 to Drupal 8" anyway, and it's in a Guide that is called "Upgrading to Drupal 8". So the link title should probably be something more descriptive, like "known issues with migrations page".
- The page it takes me to https://www.drupal.org/docs/8/upgrade/known-issues-when-upgrading-from-d... does not have current information, as it refers to work in progress on an issue that is actually marked Closed (fixed). Anyway, it tells me "If you are executing a complete upgrade at once and you are performing the upgrade to an empty Drupal 8 site, everything should be OK.". Yes, it should - I don't have any data to conflict with.
So, this warning is totally unnecessary, and is incorrect.
Proposed resolution
Don't warn the user about ID conflicts if there is no data to conflict with in the database.
Remaining tasks
Make a patch and test it.
User interface changes
No warning about data loss if there is no data to lose.
API changes
Probably not.
Data model changes
Probably not.