I think the changes for JENKINS-7108 cause problems when trying to pass a property to ant whose value is a url with multiple query parameters. For example, if you run the standalone_test target for a jsunit build, you need to pass a property like this:

url=file:///C:/Documents and Settings/hudson/.hudson/jobs/myjob/workspace/myproject/test/jsunit/jsunit/testRunner.html?testPage=c:/Documents and Settings/hudson/.hudson/jobs/myjob/workspace/myproject/test/jsunit/tests/allTests.html&autoRun=true&submitResults=localhost:8090/jsunit/acceptor

This worked in hudson 1.360 (the last one we were running before upgrading last week). After upgrading to 1.378, the parameter gets passed to the browser as:

file:///C:/Documents and Settings/hudson/.hudson/jobs/myjob/workspace/myproject/test/jsunit/jsunit/testRunner.html?testPage=c:/Documents and Settings/hudson/.hudson/jobs/myjob/workspace/myproject/test/jsunit/tests/allTests.html^&autoRun=true^&submitResults=localhost:8090/jsunit/acceptor

This causes the tests not to run.