Antenna WtkPackage produces duplicate MANIFEST.MF files

Got a strange problem with Antenna - I've recently switched over to a new laptop, and now when I copied my build setup across to it it started exhibiting strange behaviour开发者_开发百科. When I call wtkpackage (in a way that worked perfectly fine on the old laptop with exactly the same codebase), the generated JAR file contains two META-INF/MANIFEST.MF files (yes, exactly the same file path). These seem to have the same contents, and from the output from the command-line unzip tool (unzip -l myscrewedup.jar) one appears at the start of the file, one at the end. I've tried adding the duplicates="fail" attribute to the package command, but with no joy.

Has anyone else encountered this? If so, did you find a solution?

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Better answer this one in case anyone else does encounter the same problem. The problem was with the Ubunutu 11.04 setup I was using on the new laptop - for some inexplicable reason, the jar command was linked to fastjar, a C implementation of jar which evidently doesn't work properly. Switching this over to the standard Sun implementation fixed the problem immediately.