ClassicPluginStrategy.DETACHED_LIST could confuse ClassicPluginStrategyTest by injecting dependencies on split plugins that have an index.jelly.

Superfluous in that if you *want* to look at UI samples, you can just install that plugin.
And observed to cause a cyclic plugin dependency error when splitting matrix-auth from core.
(Unclear why ui-samples had a dependency on matrix-auth; perhaps related to dependency from test module.)

Fix `mvn -Plight-test install` on Ubuntu 13.04 with OpenJDK

Shaves >11min off the test time for maven-plugin on my machine!

Migrated some usages of GNUCLibrary to the jnr PosixAPI, fixed 'mvn -Plight-test install' on ubuntu with OpenJDK.

See https://github.com/jenkinsci/maven-plugin

[JENKINS-16332] Further diagnostics. Note that you must enable a hudson.model.User logger at FINE or below to use.

Merge branch 'JENKINS-19486_Polling_with_workspace_gets_incorrect_environment' of https://github.com/Vlatombe/jenkins into Vlatombe-JENKINS-19486_Polling_with_workspace_gets_incorrect_environment

[FIXED JENKINS-10675] use X-Forwarded-Proto if present

(Implies reverting c4e3adde as well, since we need resolvePluginFile to return null.)

Better wait until build is finshed and remove existing CauseAction.

[FIXED JENKINS-19251] Use hashes rather than modification time to determine if Maven agent JARs are up to date.