I'm having trouble since i upgraded from Jenkins 1.475 to 1.481. Ant verbose output states Override ignored for property "base.dir"

I'm using Apache Ant Version 1.8.4 and JDK Version 1.7.0_05

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...parsing buildfile C:\Program Files\Jenkins\jobs\somejob\workspace\somedir\build_ver.xml with URI = file:/C:/Program%20Files/Jenkins/jobs/somejob/workspace/somedir/build_ver.xml
Project base dir set to: C:\Program Files\Jenkins\jobs\somejob\workspace\somedir
Override ignored for property "base.dir"
Build sequence for target(s) `Release' is [Release]
Complete build sequence is [Release, clean_previous_build...
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