fix: check that the previous xref is not the just processed xref #669

Job	Run time
Tests alternative autoloader (PHP 7.1)	10s
Tests alternative autoloader (PHP 7.2)	7s
Tests alternative autoloader (PHP 7.3)	11s
Tests alternative autoloader (PHP 7.4)	11s
Tests alternative autoloader (PHP 8.0)	12s
Tests alternative autoloader (PHP 8.1)	6s
Tests alternative autoloader (PHP 8.2)	11s
Tests alternative autoloader (PHP 8.3)	8s
PHPUnit Composer v2 (PHP 7.4)	30s
PHPUnit (PHP 7.2)	47s
PHPUnit (PHP 7.3)	28s
PHPUnit coverage (PHP 7.4)	1m 6s
PHPUnit (PHP 7.4)	36s
PHPUnit (PHP 8.0)	35s
PHPUnit (PHP 7.1)	38s
PHPUnit (PHP 8.1)	28s
PHPUnit (PHP 8.2)	29s
PHPUnit (PHP 8.3)	31s
PHPUnit lowest deps (PHP 7.3)	29s
Windows-Tests with PHP 7.1	1m 16s
Windows-Tests with PHP 7.2	54s
Windows-Tests with PHP 7.3	59s
Windows-Tests with PHP 7.4	58s
Windows-Tests with PHP 8.0	57s
Windows-Tests with PHP 8.1	57s
Windows-Tests with PHP 8.2	1m 7s
Windows-Tests with PHP 8.3	55s
	15m 56s

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