This has started to happen recently in my laptop, when for sure it did not happen before:
The 29 tests end with 29 + 29 "* Closing connection 0" messages.
Reproduced with PHP 7.1 and 7.3. And against all branches, so it's not new.
To reproduce (or no), just run:
Surely it's some local glitch caused by some updated package here... so not critical. But as far as I've not been able to find any cause, I'm reporting this just in case it happens to anybody else.
Maybe it's the solr extension together with the curl lib it's compiled or something like that (as far as the "closing connection 0" seems to come from curl). In any case, not php problem (or phpunit would cry), but extensions one.