Aernout Peeters

In some cases, I'm getting a null pointer exception in the EnvironmentContributer class: ``` at java.util.TreeMap.putAll(TreeMap.java:313) at fabric.beta.publisher.EnvVarsContributor.buildEnvironmentFor(EnvVarsContributor.java:19) at hudson.model.Run.getEnvironment(Run.java:2287) at hudson.model.AbstractBuild.getEnvironment(AbstractBuild.java:878) at hudson.plugins.git.GitSCM.getParamExpandedRepos(GitSCM.java:419) at hudson.plugins.git.GitSCM.compareRemoteRevisionWithImpl(GitSCM.java:627) at hudson.plugins.git.GitSCM.compareRemoteRevisionWith(GitSCM.java:592) at hudson.scm.SCM.compareRemoteRevisionWith(SCM.java:391)...