python3.5 set next build number failed

[hqzhon]

use python3.5, set next build number error.I use Wireshark get the http package, then found it not contain any build_number info. the right package will contain body like this:
HTML Form URL Encoded: application/x-www-form-urlencoded
    Form item: "nextBuildNumber" = "73"
    Form item: "Jenkins-Crumb" = "a2d81d886857c3534231c03f00bf6d3d"
    Form item: "json" = "{"nextBuildNumber": "73", "Jenkins-Crumb": "a2d81d886857c3534231c03f00bf6d3d"}"
    Form item: "Submit" = "Submit"