Use Jenkins 1.509, match with git-plugin

1.509 is also needed for credentials tests
Remove maven source properties, either inherit from parent or accept default

JDK 1.5 is no longer supported by Oracle.
Additional tests of wildcards in call to getHeadRev()

Exploring change proposed for JENKINS-20767
Correct test internal behavior to match variable name

The variable name "wildOrigin" was chosen intentionally for the case
that was being tested, but then I made a mistake in later experiments
and changed the test without changing the variable name.
Merge pull request #119 from MarkEWaite/master-sync-jenkins-dependency-with-git-plugin

Sync jenkins dependency with git plugin
Added test for getHeadRev for branches with namespace
Fix for getHeadRev bug when using branch namespaces

JENKINS-20767
Apply PR feedback: Style, imports + missing fix for JGitAPIImpl
Switched back to "jenkinsci" to be on safe side

The tests will fail now until the required branches are
available in jenkinsci! For local tests you can switch
"jenkinsci" to "alexanderlink".

You have to decide how to handle tests!
Currently the productive repo is cloned for testing...
Changed test branches from "test/..." to "tests/..."

+ small refactoring
Create namespace test branches if they don't exist
Small fix for Marks test improvement + refactoring
Extracted redundant "branch spec to branch name" code
Checking for refs/heads/ in branchSpec

https://github.com/jenkinsci/git-client-plugin/pull/120/files#r10310025
comment of "dnozay"
Merge pull request #120 from alexanderlink/test/namespace3/master

Fix proposal for getHeadRev bug when using branch namespaces
Disable log entries test - new failure for an old bug

The order of log generation differs between JGit and command line git
in some cases.  Rather than allow that to stop the delivery of
git-client-plugin 1.6.4, disable the test to allow the release process
to complete successfully.
[maven-release-plugin] prepare release git-client-1.6.4
[maven-release-plugin] prepare for next development iteration
Fix deprecated JGit.setRemoteUrl(String, String, String)

Was not being tested from the unit tests, and when called was not
performing the expected operation.  The implementation now uses the
same pattern as JGit.setRemoteUrl(String, String).  That is now called
by unit tests, and passes the tests.

Also added calls to submoduleSync() without any assertions of the
results of the call.  Increases coverage slightly and will detect if
submoduleSync() throws an unexpected exception.  Further detection of
submodule errors will need to wait until the submodule tests have been
further extended.
Upgrade to JGit 3.3.0