[FIXED JENKINS-19613] 49c731f made PROXY_HEADER static under the assumption that XStream would treat that like a missing field.
Unfortunately it threw an error instead, breaking startup; fixed by renaming the constant.

(cherry picked from commit d82ba3b7524096fe571a37894c5b85091f4f45ad)
[FIXED JENKINS-19752] write in the correct outputstream

(cherry picked from commit 11fe787c0a62e70efb85935ae68b53e59f34c064)
Junit 4

(cherry picked from commit 2b2a5b4d720a188dee3a18ea8dadee89e4b8f8fa)
[JENKINS-19752] Test

(cherry picked from commit 82af0fb5622f9f913d3cad39c04eb21a2184bef8)
[JENKINS-19752] Forgotten debug statement

(cherry picked from commit ca067fd2732d480f637175f072ed0ecdb5d3478c)
[FIXED JENKINS-19251] Use hashes rather than modification time to determine if Maven agent JARs are up to date.

(cherry picked from commit 6b6a69ec0d63986d82616794d5a7fcf93df14b0e)

Conflicts:
	changelog.html
[FIXED JENKINS-19736] Installing a plugin with optional dependencies doesn't upgrade the optional dependencies when needed

(cherry picked from commit 01d5fbc2e06d76db1501ad3e24691c2643a9acd7)
[JENKINS-19447] JDK installation hangs forever

(cherry picked from commit 63bffae13bb503b3ffbef4df3ede99f9330bba93)
[JENKINS-8957] JDK installation influences already installed java instances

(cherry picked from commit 4f6e649294e27feb3afc870d0ca959e771ff9778)
[JENKINS-19307] buildEnvironmentFor job shouldn't override slave's environment with
master's

(cherry picked from commit 5ac042752ffa0a3303666acc0df1c553a9d50f15)
[JENKINS-19307] Check that Computer.currentComputer() is never called
inside buildEnvironmentFor Job since it doesn't make sense
outside of a running build.

(cherry picked from commit 5d56102232ac99ab1812884ba0633c27f82d944b)