'Jenkins for django project, failed build after many times successful building

I am using Jenkins to running my Django (Django=1.5.2, Python=2.7) project. Everything went fine before today. But now I tried to merge the updated file from git and got failed building, which stuck here:

[EnvInject] - Loading node environment variables. It took unreasonable long time and estimated running time shows N/A. 

I didn't change any settings and environment variables. What is the problem?

PS: There is one change I just found in Job Config History. Our IT guys (SYSTEM) added the code below:

<hudson.tasks.BuildTrigge>  
  <childProjects>PROJECT_NAME-Staging</childProjects>
  <threshold>
    <name>SUCCESS</name>
    <ordinal>0</ordinal>
    <color>BLUE</color>
    <completeBuild>true</completeBuild>
  </threshold>
</hudson.tasks.BuildTrigger


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