`mod()` fails for values >= .95 && < 1.0.

[kevindecapite]

When I run the DecimalModTest::testFiniteFiniteMod() test using the following data sets, I get failures:

Data Provider

            # Extant passing tests.
            ['10', '3', '1'],
            ['34', '3.4', '0'],
            ['15.1615', '3.156156', '2.536876'],
            ['15.1615', '3.156156', '2.5369', 4],
            ['-3.4', '-2', '-1.4'],
            ['3.4', '-2', '-0.6'],
            ['-3.4', '2', '0.6'],

            # New tests.
            ['0.949', '1', '0.949'],
            ['0.95', '1', '0.95'],
            ['0.99', '1', '0.99'],
            ['1', '1', '0'],

Test Results

PHPUnit 6.5.14 by Sebastian Bergmann and contributors.

Runtime:       PHP 7.2.10-1+ubuntu18.04.1+deb.sury.org+1
Configuration: /home/vagrant/www/php-bignumbers/phpunit.xml
Error:         No code coverage driver is available

........FF.                                                       11 / 11 (100%)

Time: 338 ms, Memory: 6.00MB

There were 2 failures:

1) DecimalModTest::testFiniteFiniteMod with data set #8 ('0.95', '1', '0.95')
-0.05 % 1 must be equal to 0.95, but was -0.05
Failed asserting that false is true.

/home/vagrant/www/php-bignumbers/tests/Decimal/DecimalModTest.php:37

2) DecimalModTest::testFiniteFiniteMod with data set #9 ('0.99', '1', '0.99')
-0.01 % 1 must be equal to 0.99, but was -0.01
Failed asserting that false is true.

/home/vagrant/www/php-bignumbers/tests/Decimal/DecimalModTest.php:37

However, when I run the 2 failing tests through PHP's native fmod(), I get expected results:

php > echo fmod(.95, 1);
0.95
php > echo fmod(.99, 1);
0.99
php >