------ snip ------
Schedule job Core_Builds ? core.builder
Build Core_Builds ? core.builder #28188 started
Core_Builds ? core.builder #28188 completed
Copying artifacts from Core_Builds/core.builder #28188.
ERROR: Failed to run DSL Script
hudson.util.IOException2: hudson.os.PosixException: native error calling stat: No such file or directory /jenkins_data/workspace/Core_Builds/core.builder/build/dist/release/bulletin-550.xml ENOENT
at hudson.FilePath.copyRecursiveTo(FilePath.java:1994)
at jenkins.model.StandardArtifactManager.archive(StandardArtifactManager.java:57)
at jenkins.model.StandardArtifactManager$archive.call(Unknown Source)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:42)
at jenkins.model.StandardArtifactManager$archive.call(Unknown Source)
at org.jenkinsci.plugins.buildflow.toolbox.BuildFlowToolboxDSL.slurpArtifacts(BuildFlowToolboxDSL.groovy:46)
at org.jenkinsci.plugins.buildflow.toolbox.BuildFlowToolboxDSL$slurpArtifacts.call(Unknown Source)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:42)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:108)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:116)
at Script1.run(Script1.groovy:6)
at Script1$run.call(Unknown Source)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:42)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:108)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:112)
at com.cloudbees.plugins.flow.FlowDSL.executeFlowScript(FlowDSL.groovy:82)
at com.cloudbees.plugins.flow.FlowRun$RunnerImpl.doRun(FlowRun.java:154)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:566)
at hudson.model.Run.execute(Run.java:1665)
at hudson.model.Run.run(Run.java:1612)
at com.cloudbees.plugins.flow.FlowRun.run(FlowRun.java:133)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:246)
at hudson.model.OneOffExecutor.run(OneOffExecutor.java:66)
Caused by: java.util.concurrent.ExecutionException: hudson.os.PosixException: native error calling stat: No such file or directory /jenkins_data/workspace/Core_Builds/core.builder/build/dist/release/bulletin-550.xml ENOENT
at hudson.remoting.Channel$3.adapt(Channel.java:755)
at hudson.remoting.Channel$3.adapt(Channel.java:750)
at hudson.remoting.FutureAdapter.get(FutureAdapter.java:55)
at hudson.FilePath.copyRecursiveTo(FilePath.java:1992)
... 23 more

------ snip ------

Here is my job's DSL:
------ snip ------
// build core.builder with same params.
child = build(params, "core.builder")
// save artifacts
toolbox = extension.'build-flow-toolbox'
toolbox.slurpArtifacts(child)
------ snip ------

Here is what I'm guessing is happening.

1. build child is started
2. waitForCompletion()
3. build child completes (onCompleted() fires)
4. slurpArtifacts()
5. build child gets finalized (onFinalized() fires)

Step 4 fails because artifacts are not on disk.