Edited README.md via GitHub

Edited README.md via GitHub

removing dead code lines and excess comments.   Looks good - @clarkstuth

Discovered while running the existing unit tests on PHP 8.1.

Fixes:
```
Deprecation triggered by Composer\Test\DependencyResolver\PoolBuilderTest::testPoolBuilder:
preg_match(): Passing null to parameter composer#2 ($subject) of type string is deprecated

Stack trace:
#0 [internal function]: Symfony\Bridge\PhpUnit\DeprecationErrorHandler->handleError(8192, '...', '...', 597)
composer#1 src/Composer/Package/Package.php(597): preg_match('...', NULL)
composer#2 src/Composer/DependencyResolver/PoolBuilder.php(360): Composer\Package\Package->setSourceDistReferences('...')
composer#3 src/Composer/DependencyResolver/PoolBuilder.php(338): Composer\DependencyResolver\PoolBuilder->loadPackage(Object(Composer\DependencyResolver\Request), Object(Composer\Package\CompletePackage))
composer#4 src/Composer/DependencyResolver/PoolBuilder.php(195): Composer\DependencyResolver\PoolBuilder->loadPackagesMarkedForLoading(Object(Composer\DependencyResolver\Request), Array)
composer#5 src/Composer/Repository/RepositorySet.php(229): Composer\DependencyResolver\PoolBuilder->buildPool(Array, Object(Composer\DependencyResolver\Request))
composer#6 tests/Composer/Test/DependencyResolver/PoolBuilderTest.php(110): Composer\Repository\RepositorySet->createPool(Object(Composer\DependencyResolver\Request), Object(Composer\IO\NullIO))
...
```

Discovered while running the existing unit tests on PHP 8.1.

Fixes:
```
Deprecation triggered by Composer\Test\DependencyResolver\PoolBuilderTest::testPoolBuilder:
preg_match(): Passing null to parameter composer#2 ($subject) of type string is deprecated

Stack trace:
#0 [internal function]: Symfony\Bridge\PhpUnit\DeprecationErrorHandler->handleError(8192, '...', '...', 597)
composer#1 src/Composer/Package/Package.php(597): preg_match('...', NULL)
composer#2 src/Composer/DependencyResolver/PoolBuilder.php(360): Composer\Package\Package->setSourceDistReferences('...')
composer#3 src/Composer/DependencyResolver/PoolBuilder.php(338): Composer\DependencyResolver\PoolBuilder->loadPackage(Object(Composer\DependencyResolver\Request), Object(Composer\Package\CompletePackage))
composer#4 src/Composer/DependencyResolver/PoolBuilder.php(195): Composer\DependencyResolver\PoolBuilder->loadPackagesMarkedForLoading(Object(Composer\DependencyResolver\Request), Array)
composer#5 src/Composer/Repository/RepositorySet.php(229): Composer\DependencyResolver\PoolBuilder->buildPool(Array, Object(Composer\DependencyResolver\Request))
composer#6 tests/Composer/Test/DependencyResolver/PoolBuilderTest.php(110): Composer\Repository\RepositorySet->createPool(Object(Composer\DependencyResolver\Request), Object(Composer\IO\NullIO))
...
```

Discovered while running the existing unit tests on PHP 8.1.

Fixes:
```
Deprecation triggered by Composer\Test\Downloader\FossilDownloaderTest::testUpdate:
trim(): Passing null to parameter composer#1 ($string) of type string is deprecated

Stack trace:
#0 [internal function]: Symfony\Bridge\PhpUnit\DeprecationErrorHandler->handleError(8192, '...', '...', 93)
composer#1 src/Composer/Downloader/FossilDownloader.php(93): trim(NULL)
composer#2 src/Composer/Downloader/VcsDownloader.php(267): Composer\Downloader\FossilDownloader->getLocalChanges(Object(Mock_PackageInterface_c17fec12), '...')
composer#3 src/Composer/Downloader/VcsDownloader.php(99): Composer\Downloader\VcsDownloader->cleanChanges(Object(Mock_PackageInterface_c17fec12), '...', true)
composer#4 tests/Composer/Test/Downloader/FossilDownloaderTest.php(143): Composer\Downloader\VcsDownloader->prepare('...', Object(Mock_PackageInterface_c17fec12), '...', Object(Mock_PackageInterface_c17fec12))
...
```

The default value for the `ProcessExecutor::$errorOutput` property is `null`, so the return value of `$this->process->getErrorOutput()` could well be `null`.

In that case, we may as well bypass the whole `foreach` as it will never match any of the recognized authentication failure messages.

Fixes:
```
Deprecation triggered by Composer\Test\Downloader\GitDownloaderTest::testDownloadThrowsRuntimeExceptionIfGitCommandFails:
strpos(): Passing null to parameter composer#1 ($haystack) of type string is deprecated

Stack trace:
#0 [internal function]: Symfony\Bridge\PhpUnit\DeprecationErrorHandler->handleError(8192, '...', '...', 340)
composer#1 src/Composer/Util/Git.php(340): strpos(NULL, '...')
composer#2 src/Composer/Util/Git.php(200): Composer\Util\Git->isAuthenticationFailure('...', Array)
composer#3 src/Composer/Downloader/GitDownloader.php(121): Composer\Util\Git->runCommand(Object(Closure), '...', NULL, true)
composer#4 src/Composer/Downloader/VcsDownloader.php(137): Composer\Downloader\GitDownloader->doInstall(Object(Mock_PackageInterface_f8be9ebd), '...', '...')
composer#5 tests/Composer/Test/Downloader/GitDownloaderTest.php(349): Composer\Downloader\VcsDownloader->install(Object(Mock_PackageInterface_f8be9ebd), '...')
...
```

The default value for the `ProcessExecutor::$errorOutput` property is `null`, so the return value of `$this->process->getErrorOutput()` could well be `null`.

In that case, we may as well bypass the whole `foreach` as it will never match any of the recognized authentication failure messages.

Fixes:
```
Deprecation triggered by Composer\Test\Downloader\GitDownloaderTest::testDownloadThrowsRuntimeExceptionIfGitCommandFails:
strpos(): Passing null to parameter composer#1 ($haystack) of type string is deprecated

Stack trace:
#0 [internal function]: Symfony\Bridge\PhpUnit\DeprecationErrorHandler->handleError(8192, '...', '...', 340)
composer#1 src/Composer/Util/Git.php(340): strpos(NULL, '...')
composer#2 src/Composer/Util/Git.php(200): Composer\Util\Git->isAuthenticationFailure('...', Array)
composer#3 src/Composer/Downloader/GitDownloader.php(121): Composer\Util\Git->runCommand(Object(Closure), '...', NULL, true)
composer#4 src/Composer/Downloader/VcsDownloader.php(137): Composer\Downloader\GitDownloader->doInstall(Object(Mock_PackageInterface_f8be9ebd), '...', '...')
composer#5 tests/Composer/Test/Downloader/GitDownloaderTest.php(349): Composer\Downloader\VcsDownloader->install(Object(Mock_PackageInterface_f8be9ebd), '...')
...
```

Fixes:
```
Deprecation triggered by Composer\Test\Installer\LibraryInstallerTest::testUninstall:
strpos(): Passing null to parameter composer#1 ($haystack) of type string is deprecated

Stack trace:
#0 [internal function]: Symfony\Bridge\PhpUnit\DeprecationErrorHandler->handleError(8192, '...', '...', 202)
composer#1 src/Composer/Installer/LibraryInstaller.php(202): strpos(NULL, '...')
composer#2 vendor/react/promise/src/FulfilledPromise.php(28): Composer\Installer\LibraryInstaller->Composer\Installer\{closure}(NULL)
composer#3 src/Composer/Installer/LibraryInstaller.php(208): React\Promise\FulfilledPromise->then(Object(Closure))
composer#4 tests/Composer/Test/Installer/LibraryInstallerTest.php(221): Composer\Installer\LibraryInstaller->uninstall(Object(Mock_InstalledRepositoryInterface_e3699f95), Object(Mock_Package_e4571076))
...
```

…ctation

Fixes:
```
Deprecation triggered by Composer\Test\Installer\LibraryInstallerTest::testUninstall:
strpos(): Passing null to parameter composer#1 ($haystack) of type string is deprecated

Stack trace:
#0 [internal function]: Symfony\Bridge\PhpUnit\DeprecationErrorHandler->handleError(8192, '...', '...', 202)
composer#1 src/Composer/Installer/LibraryInstaller.php(202): strpos(NULL, '...')
composer#2 vendor/react/promise/src/FulfilledPromise.php(28): Composer\Installer\LibraryInstaller->Composer\Installer\{closure}(NULL)
composer#3 src/Composer/Installer/LibraryInstaller.php(208): React\Promise\FulfilledPromise->then(Object(Closure))
composer#4 tests/Composer/Test/Installer/LibraryInstallerTest.php(221): Composer\Installer\LibraryInstaller->uninstall(Object(Mock_InstalledRepositoryInterface_e3699f95), Object(Mock_Package_e4571076))
...
```