Fix test fails on Postgres, SQLite and PHP 7

The PHP 7 tests should be fixed with this patch, now going for SQLite

Found the issue with SQLite tests, it's a core bug :(
In SQLite, indexes and tables must be unique, witch isn't the case (e.g. search_api_db_default_index_search_api_language is a table name, and search_api_db_default_index_1_search_api_language is also the name of the index of the search_api_language field in the search_api_db_default_index table.

In #1008128: Do not use a single underscore as table and index separator on PostgreSQL and SQLite there is a solution for this, but that issue was wrongly closed, as only the Postgres issues were fixed in another issue.

I'm creating a patch for that issue, but for the moment I added a temporary fix so we can test SQLite.

Hurray, all green (if you combine the 2 patches).
Maybe we should add a separate issue for SQLite, as that needs some work once the core patch in #1008128: Do not use a single underscore as table and index separator on PostgreSQL and SQLite lands?

I created a separate core issue #2625664: Name of tables and indexes conflicts for SQLite, as the patches in #1008128: Do not use a single underscore as table and index separator on PostgreSQL and SQLite are to far behind, and both for SQLite and PostgresSQL (which was fixed in #998898: Make sure that the identifiers are not more the 63 characters on PostgreSQL.

+++ b/search_api_db/src/Plugin/search_api/backend/Database.php
@@ -637,7 +637,15 @@ class Database extends BackendPluginBase {
+    // This is a quick and dirty fix for a core bug, so we can run the tests
...
+    // tl;tr: in sqlite indexes and tables can't have the same name, which is

I'd remove the tl;tr since it is actually tl;dr! :). Just make it a proper sentence.

The core issue wasn't "wrongly" closed, it didn't fully solve the initial problem. No need to blame anything or anyone in code forever.

Ow, had no intention to blame anyone, changed the comment.
Also added better explanation what the problem is.

Should we postpone this issue on #2625664: Name of tables and indexes conflicts for SQLite? I think I'd prefer getting it in like this and adding a followup to remove the changes to the database backend again that we can commit when the core issue lands? That way we can enable tests again on the currently broken builds.

In favor of getting it in like this + follow up, as we really should re-enable the tests.

+++ b/search_api_db/src/Plugin/search_api/backend/Database.php
@@ -637,7 +637,25 @@ class Database extends BackendPluginBase {
+    // This is a quick fix for a core bug, so we can run the tests with SQLite

Maybe as a last comment, add a @todo tag so we can easily find it again.

eg. @todo remove this when #2625664 gets fixed in Drupal core.

Otherwise, looks good to go. I'm RTBC'ing this but with the condition of the @todo tag.

Fixed #15, also added a new issue #2625722: Remove sqlite fixing code in search api..

We do reference the same issue 4 times. Maybe overkill but better safe than sorry?

I enabled all the environments on issue and commit now. Looking forward to having more sqlite issues! Thanks for the commit