Guzzle version(s) affected: 7.0.1
PHP version: 7.4.8
cURL version: 7.64.0

Description
I am writing a composer plugin. Whenever Guzzle is used, it throws a fatal error: Call to undefined function GuzzleHttp\Psr7\uri_for() in project/vendor/guzzlehttp/guzzle/src/Client.php:63

How to reproduce
See minimal proof of concept attached in project.zip. In the top level directory (project):

1. composer install
2. composer about

By changing the argument true to false in line 37 of project/composer-logger/src/Plugin.php, you can exclude usage of Guzzle and verify that the plugin works fine except for Guzzle.

project.zip