[MNG-4079] Fix duplication of error messages from sources like compiler errors.
Merged from: r751826,r753320 | jdcasey


git-svn-id: https://svn.apache.org/repos/asf/maven/components/branches/maven-2.1.x@755229 13f79535-47bb-0310-9956-ffa450edef68
2 files changed