WIP: bump parent pom to test JTH 2.46

[thomasgl-orange]

Following jenkinsci/jenkins-test-harness#89, jenkinsci/plugin-pom#93 and jenkinsci/git-client-plugin#393, here is a test PR to see how jenkinsci/git-plugin unit tests behave when there is a space character in their temporary workdir path.

Results are pretty good on my environment (Linux and recent git version), but for one worrisome test failure (GitSCMTest.testDataCompatibility1):

[ERROR] testDataCompatibility1(hudson.plugins.git.GitSCMTest)  Time elapsed: 9.92 s  <<< ERROR!
java.io.IOException: Failed to persist config.xml
	at hudson.model.ItemGroupMixIn.createProjectFromXML(ItemGroupMixIn.java:292)
	at jenkins.model.Jenkins.createProjectFromXML(Jenkins.java:3824)
	at hudson.plugins.git.GitSCMTest.testDataCompatibility1(GitSCMTest.java:1558)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
	at org.junit.rules.ExternalResource$1.evaluate(ExternalResource.java:48)
	at org.jvnet.hudson.test.JenkinsRule$1.evaluate(JenkinsRule.java:553)
	at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:298)
	at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:292)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.lang.Thread.run(Thread.java:748)
Caused by: javax.xml.transform.TransformerException: java.io.FileNotFoundException: /home/lwjs1183/git/jenkins-git-plugin/target/tmp/j%20h6664057865101334020/jobs/foo/config.xml (No such file or directory)
	at org.apache.xalan.transformer.TransformerIdentityImpl.createResultContentHandler(TransformerIdentityImpl.java:297)
	at org.apache.xalan.transformer.TransformerIdentityImpl.transform(TransformerIdentityImpl.java:330)
	at jenkins.util.xml.XMLUtils._transform(XMLUtils.java:212)
	at jenkins.util.xml.XMLUtils.safeTransform(XMLUtils.java:84)
	at hudson.model.ItemGroupMixIn.createProjectFromXML(ItemGroupMixIn.java:272)
	... 17 more
Caused by: java.io.FileNotFoundException: /home/.../jenkins-git-plugin/target/tmp/j%20h6664057865101334020/jobs/foo/config.xml (No such file or directory)
	at java.io.FileOutputStream.open0(Native Method)
	at java.io.FileOutputStream.open(FileOutputStream.java:270)
	at java.io.FileOutputStream.<init>(FileOutputStream.java:213)
	at java.io.FileOutputStream.<init>(FileOutputStream.java:101)
	at org.apache.xalan.transformer.TransformerIdentityImpl.createResultContentHandler(TransformerIdentityImpl.java:287)
	... 21 more

Note the URL-encoded space character in a Java File path.

I've not understood yet where it comes from, but at first glance it looks unlikely that it would be specific to this plugin unit tests, and it might rather be an issue in core...
I've tested with Jenkins 2.150.1 instead of 2.107.3, and got the same error.

Anyway, I'm opening this PR just to reproduce the issue and share with reviewers from jenkinsci/jenkins-test-harness#89.

[thomasgl-orange]

https://ci.jenkins.io/blue/organizations/jenkins/Plugins%2Fgit-plugin/detail/PR-661/1/tests

This looks very similar to this:
https://issues.jenkins-ci.org/browse/JENKINS-45512?focusedCommentId=312187

[thomasgl-orange]

Note on additional commits:

• aa2e3eb and 98a2c8a were just a test (and revert) of excluding xalan, to see how broken htmlunit would be then (results)
• f2da193 overrides javax.xml.transform.TransformerFactory, to avoid the xalan version from being used. It fixes test failures. But as discussed in jenkinsci/jenkins-test-harnessStop building excluded revisions when multiple branches are configured #89, it's not something that should be done like this in the plugin code itself, it should rather be done in JTH, or something similar

[thomasgl-orange]

f2da193 overrides javax.xml.transform.TransformerFactory, to avoid the xalan version from being used. It fixes test failures. But as discussed in jenkinsci/jenkins-test-harness#89, it's not something that should be done like this in the plugin code itself, it should rather be done in JTH, or something similar

See discussion in jenkinsci/jenkins-test-harness#89, the plan is to disable Xalan-J JAXP self-registration by maven-shading it in jenkins-test-harness-htmlunit.