Flex version 1.13.1 is broken

[abzolv]

After upgrading from 1.13.0 to 1.13.1, composer update produces an error:

PHP Fatal error: Uncaught TypeError: Argument 1 passed to Symfony\Flex\PackageJsonSynchronizer::addPackageJsonLink() must be of the type string, array given, called in /project-folder/vendor/symfony/flex/src/PackageJsonSynchronizer.php on line 46

My project composer.json has:

"extra": { "symfony": { "allow-contrib": false, "require": "4.4.*" } },

The same error happens in two separate projects, which both worked with 1.13.0.

[nicolas-grekas]

Maybe you have a global installation of flex? Please let me know how that's possible. By looking at the code, I can't figure out.

[abzolv]

A second run of composer update works as expected (doesn't crash).