avoid false failure for long path

[remicollet]

With very long path, socket path may be truncated before $socketFilePrefix,

In which case, test is failing with Socket files were not found message

This is a false failure, as the log contains the expected message:

[01-Jul-2025 05:38:07] WARNING: [pool fpm_pool] cannot bind to UNIX socket '/builddir/build/BUILD/php85-php-8.5.0_DEV.20250630-build/php-src-c9249e2d3aa401bda5d9a3071e86e0594807ed00/sapi/fpm/tests/socket-file-fpm-unix-socket-too-long-filename-but-starts-anyway-0000-0000-0000-0000-0000-0000-0000-0000-0000-0000-0000.sock' as path is too long (found length: 244, maximal length: 108), trying cut socket path instead '/builddir/build/BUILD/php85-php-8.5.0_DEV.20250630-build/php-src-c9249e2d3aa401bda5d9a3071e86e0594807ed00/s'

So only report about Socket file is the same as configured (failed test because path not truncated)

Also avoid the Warning: Undefined array key 0 in .../sapi/fpm/tests/socket-uds-too-long-filename-start.php on line 41

[remicollet]

Ping @JoshuaBehrens who adds this test

[JoshuaBehrens]

Hi @remicollet I had issues in a nixos devenv setup where the fpm socket file was in a path, that was nested deeply. I had no idea what was happening here when the socket file was not usable for communication with the webserver. So eventually it was more helpful to understand why my socket file configuration was not working. Reading up on the maximum length made sense but was not easy to find out. When you get an error message about it is much easier to spot and fix.

More on the story here #11066

Was this already helpful? :D Are you running the tests also in a directory where path is very nested? I can assume, that this might break a test setup.

[remicollet]

Hi @remicollet I had issues in a nixos devenv setup where the fpm socket file was in a path, that was nested deeply.

This change makes sense
This PR is only about the new test, failing in very deep tree (see message above)

[JoshuaBehrens]

Ah ok I got it. Makes sense to me so far :)