[JENKINS-15587] Diagnostics.
(cherry picked from commit eff5635b75a63a536f8ad24231b3eba3cbc4b63e)
[FIXED JENKINS-15587] Do not issue a warning about unparsable build timestamps if it is just a number, i.e. failed symlink.
(cherry picked from commit 06b92a49bf80debd4d9f2d334049d790d46c6081)
[FIXED JENKINS-18895] MavenModuleSetBuild.getResult is expensive.
(cherry picked from commit d1d524863cbb2f1f443fc4bf7c25933b7a31b85d)

Conflicts:
	changelog.html
[JENKINS-18895] Refined fix to not cache status during the build.
(cherry picked from commit 8d46aa6d976f5b0d89a4ad4969d455cd3a4add5c)
[FIXED JENKINS-18895] Refined fix once again.

(cherry picked from commit ec9b4f11866e80ae4a432b9127e71afddf30de86)
Revert backport of JENKINS-18776 (sometimes incorrectly refered to as JENKINS-18771)

This reverts commit f43b3cd655bd96e461649fee1e9b5ee1b5abf87a.
This reverts commit 72cea1ad5d70ed75f7d258c770f61be4ea6cb06b.
This reverts commit 01445f44e7d08ce66d443d08649ea09950175b70.
This reverts commit ce08bdf5fa5da0db0a8123857cae2cdb931f16df.
This reverts commit 448e580a3605d07599508a46e03789baa8c9308c.
This reverts commit 381ab039fa1da7d57a4ed22c4e78db2a6de34c98.
Revert "[FIXED JENKINS-14351] jna-posix → jnr-posix upgrade (opt in)."

This reverts commit 1732164817db39b9da338e1f9d9357287534a05a.

Introduced JENKINS-19192 that is too new to be backported.
[JENKINS-16974] 3c01366 was backported as eff76c7 but the merge conflict was incorrectly resolved.