sonatype/nexus — comment on commit 89e13bcea046bc27c3b94215b8d5a36e4dffea7b
File: nexus-maven-plugins/nexus-maven-plugin/src/main/java/org/sonatype/nexus/plugin/AbstractStagingMojo.java line 340
By bentmann:

As Alin correctly questioned on IRC, this method is subject to any configured mirror in mvn2, i.e. might contact a different repo than the nexus instance being intended. The only API available in mvn2 to bypass mirroring appears to be WagonManager.getArtifactMetadataFromDeploymentRepository(). This method however will apparently not use the proper user agent when used in mvn3.