Stubbed global function can not be re-stubbed after finish_spying

[mehamasum]

If a global function is stubbed once and then the original function is restored through finish_spying, the same global function can not be stubbed again.

For example,

<?php

require_once '/vendor/antecedent/patchwork/Patchwork.php';

function bar(): int {
	return 0;
}


class Test_Foo extends PHPUnit\Framework\TestCase {
	function tearDown() {
		\Spies\finish_spying();
	}


	public function test_foo_one() {
		\Spies\stub_function( 'bar' )->that_returns( 1 );
		$this->assertEquals( 1, bar() );
	}

	public function test_foo_two() {
		\Spies\stub_function( 'bar' )->that_returns( 2 );
		$this->assertEquals( 2, bar() );
	}

}

In test_foo_one, I have stubbed bar to return 1.
In test_foo_two, I have stubbed bar to return 2.
If both tests are run one after another, the first test passes and the second doesn't.

There was 1 failure:

1) Test_Foo::test_foo_two
Failed asserting that 0 matches expected 2.

The second one's bar is not stubbed and returns the original return value.

So a stubbed global function can not be re-stubbed properly.

Note: if the tests are run individually, both tests pass.