Fix builing the plugin in Jenkins' Buildhive environement
Fix builing the plugin in Jenkins' Buildhive environement

Fix taken from:
https://github.com/jenkinsci/testflight-plugin/commit/04b1ab8cc6d75cc634
e810dc72bacc50c518b09c

sq5gvm/unity3d-plugin,jenkinsci/unity3d-plugin,sq5gvm/unity3d-plugin,lacostej/jenkins-unity3d-plugin,sq5gvm/unity3d-plugin,jenkinsci/unity3d-plugin,lacostej/jenkins-unity3d-plugin,lacostej/jenkins-unity3d-plugin,jenkinsci/unity3d-plugin