We have Jenkins 2.121.2 and xunit plugin V2.1.0 and experience this issue when running with reRunFailingTestsCount property. The stack trace is :
Error when executing always post condition:
org.jenkinsci.plugins.xunit.service.TransformerException: The result file '/home/jenkins/workspace/er_feature_release-profiles-MFHVJCXJD6Z7UELFLV45A2GLPWYCH7KF5M3DEVI3EOJREF4MOSHQ/plugins/com.gresham.darwin.server.tests.integration/target/surefire-reports/TEST-com.gresham.darwin.server.tests.integration.allocations.exceptions.MatchWithAllocationsAndExceptionsIntegrationTest.xml' for the metric 'JUnit' is not valid. The result file has been skipped.
at org.jenkinsci.plugins.xunit.service.XUnitTransformerCallable.invoke(XUnitTransformerCallable.java:112)
at org.jenkinsci.plugins.xunit.service.XUnitTransformerCallable.invoke(XUnitTransformerCallable.java:39)
at hudson.FilePath$FileCallableWrapper.call(FilePath.java:2913)
I had submit a PR for this