composer: Failed to decode response: zlib_decode(): data error

Don’t know why but I have an issue here on updating/installing etc…

I know there is a very long discussion on the topic #4121 and an article over here but none of these recommendations helped.

The actual very weird thing is: On friday everything worked still fine.

Getting the same issue on different machines (linux/windows) and on our ci-server

local:

$ php composer.phar update
Loading composer repositories with package information
Updating dependencies (including require-dev)
Failed to decode response: zlib_decode(): data error
Retrying with degraded mode, check https://getcomposer.org/doc/articles/troubleshooting.md#degraded-mode for more info
zlib_decode(): data error
http://packagist.org could not be fully loaded, package information was loaded from the local cache and may be out of date

Jenkins:

vendors:
     [exec] Loading composer repositories with package information
     [exec] Updating dependencies (including require-dev)
     [exec] Failed to decode response: zlib_decode(): data error
     [exec] Retrying with degraded mode, check https://getcomposer.org/doc/articles/troubleshooting.md#degraded-mode for more info
     [exec] zlib_decode(): data error
     [exec] http://packagist.org could not be fully loaded, package information was loaded from the local cache and may be out of date
     [exec] Nothing to install or update
     [exec] Writing lock file
     [exec] Generating autoload files

I don’t have any idea whats wrong 😦

EDIT:

$ php composer.phar diagnose
Checking composer.json: OK
Checking platform settings: OK
Checking git settings: OK
Checking http connectivity to packagist: OK
Checking https connectivity to packagist: OK
Checking github.com rate limit: OK
Checking disk free space: OK
Checking pubkeys: 
Tags Public Key Fingerprint: 57815BA2 7E54DC31 7ECC7CC5 573090D0  87719BA6 8F3BB723 4E5D42D0 84A14642
Dev Public Key Fingerprint: 4AC45767 E5EC2265 2F0C1167 CBBB8A2B  0C708369 153E328C AD90147D AFE50952
OK
Checking composer version: OK

Why is diagnose not testing for the zlib_decode functionality?