Avoid need for idealNames workaround

[basil]

Testing with

diff --git a/src/test/java/org/jenkinsci/plugins/workflow/multibranch/WorkflowMultiBranchProjectTest.java b/src/test/java/org/jenkinsci/plugins/workflow/multibranch/WorkflowMultiBranchProjectTest.java
index 86d2af8..501a484 100644
--- a/src/test/java/org/jenkinsci/plugins/workflow/multibranch/WorkflowMultiBranchProjectTest.java
+++ b/src/test/java/org/jenkinsci/plugins/workflow/multibranch/WorkflowMultiBranchProjectTest.java
@@ -233,7 +233,7 @@ public class WorkflowMultiBranchProjectTest {
     @Test public void configuredScriptNameBranches() throws Exception {
         sampleRepo.init();
 
-        WorkflowMultiBranchProject mp = r.jenkins.createProject(WorkflowMultiBranchProject.class, "p");
+        WorkflowMultiBranchProject mp = r.jenkins.createProject(WorkflowMultiBranchProject.class, "ElNiño");
         mp.getSourcesList().add(new BranchSource(new GitSCMSource(null, sampleRepo.toString(), "", "*", "", false), new DefaultBranchPropertyStrategy(new BranchProperty[0])));
         for (SCMSource source : mp.getSCMSources()) {
             assertEquals(mp, source.getOwner());
@@ -248,30 +248,30 @@ public class WorkflowMultiBranchProjectTest {
         mp.scheduleBuild2(0).getFuture().get();
         assertNull(mp.getItem("master"));
 
-        sampleRepo.git("checkout", "-b", "feature");
+        sampleRepo.git("checkout", "-b", "feature/1");
         sampleRepo.write("another-Jenkinsfile", "echo(/branch=$BRANCH_NAME/); node {checkout scm; echo readFile('file')}");
         sampleRepo.git("add", "another-Jenkinsfile");
         sampleRepo.write("file", "subsequent content");
         sampleRepo.git("commit", "--all", "--message=feature-create");
-        WorkflowJob p1 = scheduleAndFindBranchProject(mp, "feature");
+        WorkflowJob p1 = scheduleAndFindBranchProject(mp, "feature/1");
         assertEquals(1, mp.getItems().size());
         r.waitUntilNoActivity();
         WorkflowRun b1 = p1.getLastBuild();
         assertEquals(1, b1.getNumber());
         r.assertLogContains("subsequent content", b1);
-        r.assertLogContains("branch=feature", b1);
+        r.assertLogContains("branch=feature/1", b1);
 
-        sampleRepo.git("checkout", "-b", "feature2");
+        sampleRepo.git("checkout", "-b", "feature/2");
         sampleRepo.write("another-Jenkinsfile", "echo(/branch=$BRANCH_NAME/); node {checkout scm; echo readFile('file').toUpperCase()}");
         sampleRepo.write("file", "alternative content");
         sampleRepo.git("commit", "--all", "--message=feature2-create");
-        WorkflowJob p2 = scheduleAndFindBranchProject(mp, "feature2");
+        WorkflowJob p2 = scheduleAndFindBranchProject(mp, "feature/2");
         assertEquals(2, mp.getItems().size());
         r.waitUntilNoActivity();
         WorkflowRun b2 = p2.getLastBuild();
         assertEquals(1, b2.getNumber());
         r.assertLogContains("ALTERNATIVE CONTENT", b2);
-        r.assertLogContains("branch=feature2", b2);
+        r.assertLogContains("branch=feature/2", b2);
     }
 
     @Issue("JENKINS-72613")

I tested to see if the idealNames workaround in cloudbees-folder was still necessary. I found a usage here:

idealNameFromItem:151, ChildNameGenerator (com.cloudbees.hudson.plugins.folder)
dirNameFromItem:248, MultiBranchProjectDescriptor$ChildNameGeneratorImpl (jenkins.branch)
dirNameFromItem:222, MultiBranchProjectDescriptor$ChildNameGeneratorImpl (jenkins.branch)
dirName:198, ChildNameGenerator (com.cloudbees.hudson.plugins.folder)
getRootDirFor:543, AbstractFolder (com.cloudbees.hudson.plugins.folder)
getRootDirFor:878, MultiBranchProject (jenkins.branch)
getRootDirFor:130, MultiBranchProject (jenkins.branch)
getRootDir:196, AbstractItem (hudson.model)
getConfigFile:391, Items (hudson.model)
getConfigFile:624, AbstractItem (hudson.model)
save:619, AbstractItem (hudson.model)
save:203, Job (hudson.model)
setDefinition:172, WorkflowJob (org.jenkinsci.plugins.workflow.job)
setBranch:66, AbstractWorkflowBranchProjectFactory (org.jenkinsci.plugins.workflow.multibranch)
newInstance:55, AbstractWorkflowBranchProjectFactory (org.jenkinsci.plugins.workflow.multibranch)
newInstance:45, AbstractWorkflowBranchProjectFactory (org.jenkinsci.plugins.workflow.multibranch)
observeNew:2109, MultiBranchProject$SCMHeadObserverImpl (jenkins.branch)
observe:2031, MultiBranchProject$SCMHeadObserverImpl (jenkins.branch)
process:357, SCMSourceRequest (jenkins.scm.api.trait)
discoverBranches:728, AbstractGitSCMSource$8 (jenkins.plugins.git)
run:632, AbstractGitSCMSource$8 (jenkins.plugins.git)
run:611, AbstractGitSCMSource$8 (jenkins.plugins.git)
doRetrieve:415, AbstractGitSCMSource (jenkins.plugins.git)
doRetrieve:352, AbstractGitSCMSource (jenkins.plugins.git)
retrieve:611, AbstractGitSCMSource (jenkins.plugins.git)
_retrieve:372, SCMSource (jenkins.scm.api)
fetch:282, SCMSource (jenkins.scm.api)
computeChildren:662, MultiBranchProject (jenkins.branch)
updateChildren:272, ComputedFolder (com.cloudbees.hudson.plugins.folder.computed)
run:171, FolderComputation (com.cloudbees.hudson.plugins.folder.computed)
run:1065, MultiBranchProject$BranchIndexing (jenkins.branch)
execute:101, ResourceController (hudson.model)
run:445, Executor (hudson.model)

This must have been the problem @stephenc had in mind when he wrote:

There are some items which need the Item#getRootDir() during construction (those are bold evil item types that leak side-effects, you should fix them if you find them).

I have found it, and I am fixing it. Here the problem is that WorkflowJob#setDefinition triggers a save (which needs the unmangled name) before we have added the BranchJobProperty to record the unmangled name. By wrapping the whole thing in a BulkChange we avoid the save until after the unmangled name has been recorded in BranchJobProperty, after which idealNames is no longer consulted.

Testing done

PR build, as well as local testing with the abovementioned test diff. Verified in the debugger that idealNames was consulted before this PR but not after this PR.

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests - that demonstrates feature works or fixes the issue

[basil]

Review with Hide whitespace enabled.

[jglick]

WorkflowMultiBranchProject mp = r.jenkins.createProject(WorkflowMultiBranchProject.class, "ElNiño");

Just to be on the safe side I guess? Since my understanding is that the affected code deals with the relative names of Jobs with the ComputedFolder, not about the name of the ComputedFolder itself.

[jglick]

Will be great to get rid of this system if we can.