The last version 19\.1 of pip contains a major regression \[1\] which makes all CI tests fails \[2\]\. \ This prevents to prepare release \(or any push\) with a correct feedback about successful tests\. \ So the release and any non\-critical development are blocked until a working version of pip is released\. \ \ We are stuck with the last published version of pip because it is the behavior of tox to always install the latest version\. \ The CI can not be tuned to ignore a specific release of a package because it directly talk to pypi\.org\. \ \ \[1\] https\:\/\/github\.com\/pypa\/pip\/issues\/6437 \ \[2\] https\:\/\/drone\.tryton\.org\/tryton\/modules\.account\_invoice\/176